Ranked choice is fine, but it’s never going to end the two party system on its own. We can already see in some states (Alaska and Maine) and in some smaller municipalities in the US, and in countries outside the US, which have switched to RCV after having a 2-parety system that it doesn’t end the 2-party system. At best, it makes campaigning a little less negative.

People tend to simplify the concept of 3rd parties when thinking about RCV. They get it in their head that everyone who dislikes the 2 major parties would all vote for the same 3rd party as a first choice under RCV. In practice, that’s not how it works. Most people still vote for one of the major parties as their top choice. Among those who don’t, they are extremely divided in which 3rd party they pick. People who traditionally vote Republican but don’t really like them may be willing to vote Libertarian, but their never going to vote Green. Likewise, someone who doesn’t really like the Democrats but typically votes for them might prefer the Green Party or DSA or something, but they’re not voting Libertarian or Freedom Party.

When RCV is implemented in a 2-party system, what almost always happens is that the first choice 3rd party vote gets split among a number of different 3rd parties, giving none of them enough votes to win. When those get dropped in the first round of instant run-offs and those votes switch to the 2nd choice, one of the 2 major parties almost always wins.

If you want to get rid of the 2-party system, you need to get rid of single-member congressional districts. Switch to multi-member districts with proportional representation. Say a state gets 5 Representatives to the House. Each party (including 3rd party) puts forth up to 5 candidates all running in the same race. Everyone votes for either their preferred candidate or preferred party (you can even implement RCV here to rank candidates if you want). Then seats are allocated to each party based on which proportion of the vote they get. If the Green party gets 20% of the vote, they get 1 seat. If Republicans get 40%, they get 2 seats, etc, etc. The specific candidate(s) who wins from each party would be whoever got the most votes within that party.

This almost eliminates strategic voting. You don’t have to worry that your party is small with nowhere close to a majority support because you don’t need a majority to win a seat. Nearly everyone gets the representation they want.