It’s very tempting to solo the part/instrument you are EQ’ing. You should try to avoid doing this however.
Your mix is a sum of all its different elements but the funny thing is, in music 1+1 doesn’t always equal 2. The brain has its own (very complex) way of calculating things. The way you perceive an EQ adjustment on an individual track depends a lot on what else you have going in the mix.
Any adjustments are therefore best made within the context of the entire mix. If you adjust everything on solo you’ll have a much harder time achieving a well-balanced mix.
It’s fine of course to listen on solo to figure things out and get a better picture of what’s going on. But you want your ears/brain to have all the necessary information to make the right decisions.