I rooted my S10+ and I followed this YouTube guide:
If you haven't done it already then before you start following anything in that video you have to unlock the bootloader on your phone. That is fairly simple and if you don't know how to do that then if you look at that same YouTube channel (Explaining Android) then you'll find another video showing how to do it.
What I would suggest is watch the video a few times. Make sure you have all the right files on your PC / laptop. If you don't have it already you will need Odin installed on your PC and also I would suggest using Frija to download your phones software files. Very important to make sure you download the correct ones.
One last bit of advice. If you're not 100% comfortable and certain you know what you're doing then don't do it. Last thing you want to do is brick your phone.