disclaimer: I’m just asking to get understanding of the theory behind network traffic encryption, I know this doesn’t happen irl most likely.

Let’s take https connection for example. I like watching revolutionary things on youtube and do not wish for authorities to know what I am watching, we accept here for the sake of showcase that google won’t sell my watch history if asked (LMAO what am I even saying?).
So if I’m not mistaken since youtube has https implemented, our communication is encrypted, the keys are shared only between me and youtube. But when Youtube shares the key with me/my client the first time, is that also encrypted? Wouldn’t the same question keep getting answered until there is something unencrypted? I know this is a bit too much unlikely, but if ISP automated the process of gathering keys and decrypting web traffic for a certain site with them for all users, would that work for them?
I’m taking https here as an example, while I have the same question for like VPN.

EDIT: Thank you everybody. I am not a member of this community, but every comment was a golden experience to read!