You can find many very small timers running music selling software on a little site who may have little understanding to the legal issues, it's probably safest to deal with an established business, the top site with the budget to promote themselves with paid ads is:
https://www.payloadz.com/aw-sell-beats-o...
You can certainly "give away" your creative property for free, which is what you'd be doing, in effect, if you have no written contract that says otherwise.
Of course, you can publish your own works and ask people making copies to pay you a royalty, since you own the copyright of your original creations.
You CAN NOT sell to MAJOR artists without a contract.
Without a contract, you could later lie and ay that they stole the beat from you, and sue them.
THEY will REQUIRES a contract so that both they and you know exactly what they bought and for what purpose and for how long.
A CONTRACT HELPS KEEP YOU AND THEM SAFE FROM LIARS AND CHEATERS, and the music industry is FULL of both of these!
Hahaha... no. I could get into the legal details of it but it probably won't benefit anyone. I'll leave it at this: Anyone with the money to pay for your music will want EVERYTHING written down and signed in triplicate, if only to cover their own ***. Anyone who doesn't do this is an idiot.
For your own protection, you would need contracts, and those who know how to do that well. Otherwise, you don't control the terms and conditions of the use of your work, and people can and will take advantage.
I know this is dumb, BUT...is there a way to sell beats to MAJOR artists without contracts, lawyers, copyrights, PROs or whatever, and still be in control of your material and make money?