Let's start with the agenda part of this, and work our way back to globalism.
According to Conservapedia, the agenda being sought by "globalists" includes these items - comment attached here.
"'harmonizing' our laws with foreign ones, rather than vice-versa." In practice, this works now as it always has, in areas where nations think cooperation is a wise thing: They negotiate. The same thing happens among states in the United States when they try to develop common laws so that commerce, travel, communications and more aren't hopelessly snarled by passage across state lines. It's not new; the idea goes back a few centuries.
"amnesty for illegal aliens, open borders, no border wall." The concept of open borders - see the entry for that in WDYMBT - is not completely imaginary, but as concerns the United States is held by few people, no massive group of globalists. Nearly all nations around the world enforce restrictions on passing through their borders, so how an anti-borders approach would be the domain of globalists is hard to feature. As for the practicality of a border wall (presumably, to judge from the conversation, with Mexico) ... that would be a fantasy.
"more visas for guest workers" Requests for those usually are generated by local, American, businesses.
"repealing the Second Amendment" There is no meaningful such effort in existence, imaginations of certain of its advocates notwithstanding.
"eliminating the abortion issue from politics by making Roe v. Wade permanent" Nothing in American government or politics is permanent; to the degree Roe is established law (via court decision), it already is and has been since 1973. Nothing else short of constitutional amendment (which isn't on the horizon) could make it more so. But even in that case, abortion would not be eliminated from American politics as long as people want to debate it. The Roe decision certainly didn't accomplish that. Taken as a whole, this stated goal must be the most ludicrous of the bunch.
"repealing the Electoral College" Hard to see how moving the process of electing a president from an otherwise obscure national group to the outright selection of the voters of the United States would serve global rather than American interests. You'd think it might more logically be the other way around.
"a parliamentary style of government" There's no push for that in the United States, though there are some arguments that such as approach might be more efficient than what we have. It's debatable. But hard to see how it would diminish natural sovereignty.
"repealing the Treaty Clause" This is a real puzzler. The Treaty Clause is the provision in the U.S. Constitution which describes how treaties are approved (the president negotiates and proposes them to the Senate, which can approve them with a two-thirds favorable vote). Maybe someone somewhere has an alternative procedures to propose, but any proposal to actually repeal this provision has kept very, very quiet. If (as is unlikely) it exists.
"supporting many unnecessary treaties, like NAFTA and the Paris climate agreement, which don't receive Senate approval" Not all international agreements are formal - binding - treaties; some do not require Senate approval. as to what's necessary or useful, opinions may vary.
"removing state sovereignty and, eventually, establishing a one-world government" Here presumably we get to the core of the thing, and the heart of the paranoia.
"One-world government" (which probably will get its own entry here before long, it being apparently not yet a gone-away phrase) is an old faithful bogeyman, going back generations and no closer to reality now - even in a time of much accelerated communication and transportation - than it ever was. And you will have to look with a microscope to find anyone in American politics, or really the politics of any other country, who would support it.
A letter to the editor of the Washington Times added this: "It is amazing to me that so many people are unable to see through the scam of 'climate change.' This goes right along with the bogus Islamic immigration policies being pushed on Western nations. Such policies, clear as can be, are being pushed on Western countries by the global elitists. They want to destroy Western culture and capitalism as we know it. In addition, they want to bring on a one-world religion and blend Islam into the mix."
Why these elites, who presumably are overwhelmingly white Western secular capitalists, would be so eager to do all this, is unclear ... the say the least.
So much for the agenda. So what's left for globalism?
The Conservapedia entry starts out with this description: "Globalism is the failed liberal authoritarian desire for a "one world" view that rejects the important role of nations in protecting values and encouraging productivity. Globalism is anti-American in encouraging Americans to adopt a "world view" rather than an "American view." The ultimate goal of globalism is the eventual unification of humanity under a one-world government. Communists and Marxists are using globalization to advance their political aims."
Considering the near-complete collapse of communism around the globe a generation ago, this doesn't seem to be working out very well for them.
There are some alternative, less ideological, ways of looking at the idea of a trans-national cooperative effort, however. The idea that power is perfectly siloed within national borders is clearly invalid in a day of multinational corporations, international finance, global military systems and worldwide instant communications.
Writer Jeremy James in one recent paper (its dating is unclear) wrote that "many dismiss those who believe in a global conspiracy as cranks and fools." He goes on to point out, however, to offer this definition: "A secret agreement by a number of super-rich families to increase their wealth and power on the world stage by covert means, with a view ultimately to impose a unified world government under their control ..."
There are in fact wealthy interests - some familial, some not - around the globe whose tentacles reach across dozens or scores of nations, and surely they sometimes talk to each other, and no doubt cooperate. But the real world, they're not going to agree all the time, and their practical ability to cooperate in a thriller novel is not much better than the ability of most any other group of disparate people to operate like a well-oiled machine. The idea is an exposure of an unawareness of how people and organizations work in the real world.
There is another, maybe darker, aspect to the "globalist" label.
Writer Peter Beinart put it this way: "The term “globalist” is a bit like the term “thug.” It’s an epithet that is disproportionately directed at a particular minority group. Just as “thug” is often used to invoke the stereotype that African Americans are violent, “globalist” can play on the stereotype that Jews are disloyal. Used that way, it becomes a modern-day vessel for an ancient slur: that Jews—whether loyal to international Judaism or international capitalism or international communism or international Zionism—aren’t loyal to the countries in which they live."