Where to start?

I’m 19M and I’ve always loved music but only started to learn to play piano last year self taught (currently around a grade 4-5 maybe) and I started the guitar this year. I’ve always enjoyed singing along to songs when they’re playing out loud. But, my singing isn’t exactly the best and I’m not very confident with the singing when there is no music, so it ends up sounding worse.

I’m wondering where could I start, to learn singing, self taught.

Any advice or videos I can use to learn?