You "need" to be on all social media, but depending on your niche depends on what social media will benifit you more. Judging by the guitar it looks like you're probably a musician. In that regard if you do original music, maybe TikTok, instagram (Igtv and instagram clip music videos can do well if the music is entertaining)
I'd recommend twitter as a bit of a glimpse vlog. a quick paragraph of what you're up to today, a quick paragraph of your views or frustrations as a creator (be warned, twitter can be a dumpster fire of trolls and opinions)
Instagram is generally pretty safe for music.
Oh, and this may be counter intuitive to youtube, but try Twitch! You'd be surprised how good twich can be for musicians. Browse twitch and watch the "music" category https://www.twitch.tv/directory/game/Music
and just watch and see how they do things. There's a channel called "younggun" who has 42k followers on twitch which is MASSIVE on that platform. 100k followers on twitch is equivilant of 1million subscribers on YouTube, I've seen lots of verified channels on twitch with 1k-3k followers who do very well for themselves.
Twitch doesn't allow you to keep vidoes on demand (vods) for long though, so I'd use it as a platform to practice, and you can post the results of that onto your YouTube, promote your streams with twitter, share new videos on twitter and then spend some time on twitter sharing what you're up to, maybe you watched a cool movie, want to share some quick thoughts on musicians and the music industry, then you can take little 30 second snippets of songs, post them to your instagram with a link in your bio to a linktree which links out to all your socials. Stories on instagram are also good little snapshots into your daily music life in 10ish second snippets that will go away in 24 hours.
You can do 1 hour streams on instagram (not the most discoverable though, that's more of a thing to do when you've already got an established following.
So my recommendation is 1 Twitch, 2 Instagram, 3 twitter.