How do I convince my cat that I am, in fact, the one in charge here?
I admire the ambition, but I should be honest with you: you are not going to win this one.
Control the food. Be the sole dispenser of treats. Establish a routine so ironclad that the cat associates your presence with reliable comfort rather than chaos.
The cat will accept the food, interpret the routine as the bare minimum expected of a servant, and continue to knock things off tables while maintaining direct eye contact.
You are not in charge. You are a beloved and well-compensated employee. The benefits are excellent (warmth, purring, the occasional dead moth as a bonus). Lean into it.