Replacing First Past The Post voting with a more representative electoral system such as Ranked Choice voting would allow more then 2 political parties to be viable with no spoiler effect.

As a result, the Democratic Party and the Republican Party would oppose getting rid of First Past the Post because it gives them an advantage in elections. So, in order to get rid of First Past the Post, you would need to first elect a third party. Unfortunately, because of First Past the Post, you're not going to be able to elect a third party.