Centminmod answered there that you can find ImageMagick from epel-testing and remi.
I don’t have CentOS 8 so I can’t test it. I just believe that’s true. I’m sorry if it’s not.
Available Packages
ImageMagick.x86_64 6.9.10.64-1.el8 epel-testing
ImageMagick.x86_64 1:6.9.10.65-1.el8.remi remi
ImageMagick.x86_64 1:6.9.10.66-1.el8.remi remi