Listen to a lot of Rap

Listen to a lot of rap: Listen to a wide variety of rap styles to see the different approaches by era!
See if you like the genre of rap, 5 songs from different artists should be enough to see if you like the style or not.
See these articles to help you discover new ones:

Try

Search for instrumentals in the style of your favorite genres or artists (try several, it is rare to find directly what you are looking for). For example, you can search for “Style name or artist + Beat type” on Youtube or any other place you like. Try rapping over different types of beats to see what works best for you. You can use beats from different rap styles to see what works best for you.

Find your Voice

Find your voice : This is REALLY not the first thing to do, have fun following the first 2 steps, and ONLY once you have found an adequate flow, and you know how to pose in time, only then, try several intonations, and several tones, pitches, to see what sounds best, asking a sincere friend for help can help, and if not try to record yourself and listen (even if it can be hard to judge yourself).

Stay yourself

Be yourself: Don’t try to imitate other rappers (unless it’s really your goal). The key is to know what’s out there, while trying to do things your way, feel free to take inspiration from some rappers, and adapt it to your own universe, but don’t imitate only one rapper, also get out of your comfort zone by trying unexpected things, and have fun! (some people forget this)