As a user, you can:

• Review instance and community rules prior to participating
• Review the moderator logs to confirm that moderation activities have been in line with the rules
• If you notice a discrepancy, e.g., over-moderation, you can hold the mods accountable and draw attention to it or simply choose not to engage in that instance or community
• Host your own instance
• Create communities in an existing instance or your own instance

If you host your own instance and communities within that instance, then at that point, you have full control, right? Other instances can de-federate from yours.