Almost 5 year old thinks he's the parent

This is my first post. I have tried to gentle parent my 4 (almost 5 year old) his whole life. I haven't always been successful, but I have tried really hard.

Lately, he has been having more tantrums and power struggles over trying to tell my SO and me what to do. It's like he thinks he is the parent. For example, "It's not fair that you get to watch tv whenever you want. You have to let me do whatever you do!" Cue a meltdown where he continues to repeat himself, talk over me, scream, etc. I tried for a little bit to explain why he can't just watch TV whenever he wants, but eventually I just carried him to his room and told him to pick a coping strategy from his basket of calm tools. He screamed at me to go away, so I did. He was still crying when he came back out, but he was calm enough to sit and eat his food. (This was during lunch.)

I'm not one of those "never say no" parents. I try to compromise when I can, but I definitely say no when it comes to health and safety. I also don't typically let him tell me what to do. He's been mostly doing this with me, but I'm also the default parent. Nothing has changed that I can think of. Please help. I'm so tired of the tantrums!