

This won’t do it. The plurality system (often called “first past the post”) inherently and inevitably leads to 2 parties. Whenever a third is introduced successfully, it quickly eliminates one of the previous parties.
Breaking up the supply duopoly requires a change in voting method, such as Ranked Choice or Approval methods. Those allow a third party without acting as a spoiler.
Imagine choosing Trump over your own wife, even if you hate her.