The number of third party votes has gone up and down a little, but over the last 40 years the only third party candidate to get over 5% of the vote in a presidential election was Ross Perot. 2020 actually had very low third party support. The most popular third party candidate left of the Republican party in the last 40 years was Ralph Nader in 2000, and he got about 2.5% of the vote. There will almost certainly be more people voting for third parties in 2024 than there were in 2020, but unless something very weird happens between now and November it will probably just be going back to normal. 3-4% Libertarian and 1-2% Green. That’s not gonna do much of anything.