Social media presence as in having accounts in your name with you being visible in the profile picture in mainstream sites (Anything Meta, Twitter, Snapchat, Tiktok…). I don’t consider anynounmous accounts on Lemmy, Reddit, Kbin relevant to the scope of this question.
Depends entirely on the person and what things they want out of a social life.
For me, if I didn’t have social media, there’s a lot I’d miss out on. It’s how two of my main social communities communicate any of their events, and it’s a big part of a third. There would definitely be a negative impact for me if I nuked all my accounts.
You can certainly build your life to have your definition of a thriving social life without it, but you’ll have to go out of your way to find those groups that use other methods for communication.