No, but they decide the moderation policy that incentivizes the content produced (by nature of selecting which users feel comfortable using their product and which do not).

For example, I do not feel comfortable using the same platform as people that post child sexual abuse material. X's Grok is infamous for generating such content on demand. I opt to use platforms that do not have this as a first-class feature. X has selected against my participation and for the participations of people who hold a contrary opinion to me. Even if Grok stops producing CSAM, that selection bias will persist.