"Take the power back" by not continuing to give them your money.
Google makes money off of advertising. Apple makes money, in part, off of taxing apps. If Apple can't tax apps, then suddenly their business model isn't nearly as appealing, and they start needing to make changes to keep things profitable -- things like maybe selling more of your data, or "encouraging" you to upgrade by not supporting older phones as well.
This whole discussion always makes me angry because right now I have a choice: I can choose to buy a product supported by app taxes, or I can choose to buy a product supported by spying on me. If Apple is forced to allow other app stores, and thus forced to look for other business models to remain profitable, I may not have that choice any more.
If Fortnite doesn't like it, why don't they just charge 50% more for the app on iOS? If people complain, just show them the math, so they know that it's the Apple Tax making things more expensive. I'm happy to pay 30% more for apps.