Some people have seen the update while the rest of us are still waiting for it depending on the carrier you have and the region you're in. After your carrier varifies it and tests it then the update will be pushed out to your phone. You can manually check for updates unfortunately the only thing to do now is wait until your phone indicates the One UI 2.1 update is available.
Only Verizon and Sprint got the latest UI 2.1 update but T-mobile and At&t still working on it. Hopefully it will arrive soon. I have s10 plus T-mobile and still haven't receive any update yet.