This varies from model to model.
Most graphics cards GPU runs in the 75-85' C range, however it can run up to 90'c safely. If you have a newer graphics card that also has a Junction/Hotspot temperature reading this will usually run in the 85-95' Celsius range, but some models may run into the 100's Celsius safely. You can use the AMD settings to monitor temperatures, or something like GPU-Z https://www.techpowerup.com/gpuz/ .