The question is too broad ... you need to be more detailed about what you are trying to achieve. Something like Facebook? Something like TikTok? Something like Twitter?
Video sharing? Audio? GIFs?
Replies? Discussions? Groups? DMs and PMs?
Who is your audience? People who can install Docker? Or people who don't know the difference between a browser and an "app"?
Look up and read about XMPP, Matrix, and ActivityPub. Here's a document:
https://docs.joinmastodon.org/
That talks a little about the protocols and the software and might serve as a reasonable starting point.
