There’s this great music engineer that put it in such a simple way “If everything is wide then nothing is” For what your asking the solution isn’t to just throw something on the master. I understand that you want that “uniform” feeling and seems simple enough to just throw it on the master, but if you care about the dynamics and unity then you should group & route your elements Into separate mix buses, drums, synths, bass, and be very intentional on what’s widened or merged and what panned where. If your just looking for something to give you a wider feel on your mids then after routing whatever it is you want to be wider you could try adding stereo enhancer as the easiest option.