How to improve sound quality, especially with vocals

i'm a pretty good singer, and I want to start making content on TikTok, but my audio is almost end up sounding childish because of how the audio is recorded, when directly recording from my phone (in Tiktok app)

and I see people, who are also really good vocalist, sound great and it looks like they're just recording into their phone.

obviously, it's possible that that's not the case.

But regardless, how can I get my audios on TikTok to sound clean like other clips?