Do you mean 'free & royalty free' OR just 'royalty free'?
I use ChillHop Music on my channel. They are free and royalties free as long as you credit them exactly like they want. BUT only for YouTube. not twitch or TikTok (at least not yet). To be clear they have a creator platform that you link to your channel before you can start using their music.
If I'm working on a paid video, i typically use PremiumBeat.com. All the music is royalty free but you do need to buy it.
Just to make sure anyone else coming to this thread is on the same page, royalty free just means you don't have to pay for every view the video gets.