Improving the sound of exported files

I’ve been learning Audacity by trial and error (whereas of course I should have come here first), and I have a number of files that have been mixed down and exported as wav files. If I stupidly do not have the saved project files is there much I can do in Audacity with the mixed down wavs if I still want to improve the sound? Specifically I don’t understand eq’ing too well yet. Is that going to help much if I don’t like the mix that’s been exported, or have I blown it?

Here’s what’s supposed to happen.

You capture one or more live performances and Export each one as WAV. If it’s important enough, copy each WAV file to backup drive or other media. Lock in closet.

Open each of the main WAV files in audacity and produce and edit your brains out, Saving a Project as you go. When you get to the final show, save the Project and Export As WAV to get your output sound file. (Audacity, a you know, doesn’t Save sound files).

If you missed any of those steps, you can’t ever go back and change anything other than things you can do to the whole show at once. You can’t make the violins louder, but you can make the whole orchestra louder; or brighter with the EQ tools, etc.