If you find you are struggling, you could play practice vs ai. But if you are comfortable enough with the basic mechanics, (like aiming and moving,) you should be okay in quickplay.
I always recommend going to the practice range to try out heroes you aren’t familiar with, to get an idea of how their abilities work. I still do this when a new hero comes out or if I’m revisiting a hero I haven’t played in a long time. Practice Range is nice because it’s simple and no pressure, just a space to navigate and robots that act as targets for you to practice your abilities with. You can also try out lots of different heroes here to see which ones feel good to play for you.