In a multiplayer game, the client renders and accepts inputs.

Then, you can also just freely release the server hosting software, as was the norm in gaming, for decades.

Ever hosted a private server for anything? Batllefield 2? HL2DM? Quake 3? Minecraft? Conan Exiles? Arma 1 2 or 3? etc?

Shit, even the original Deus Ex has a mutiplayer component, that you can host a private server for.

There's no reason that a client being subservient to the server, in a multiplayer setting, means that nececassrily you don't control the game client.

What you are thinking of is a 'thin client', where the client is now not even doing rendering of the game, its just accepting player inputs, and your gameplay is actually you watching a livestream being rendered somewhere else.

Thats not the same thing as deisgning the client and server in a clever way such that the client cannot force things onto the server that it should not be able to.