An example would be what was done with AIM. As a condition of AOL merging with Time Warner, AOL had to agree to allow competitors to interoperate with AIM: https://www.itworldcanada.com/article/aol-near-release-of-in...

Many of the other potential actions are similar to those already proposed or imposed upon Google in various European or other international jurisdictions. Though some of the search engine choice screen options have proven ineffective, and if the US wants to carry that forward, they might need to prohibit auctioning off the slots or other methods that just serve to add to Google's revenue at the expense of everyone else.