Everyone in my group still wears stock ties unless the shirt has an integrated one. I think part of it is we bought them before the rules changed so we’re going to use them! Same with breeches. We all have good white breeches. Maybe once they need to be replaced we’ll branch out to other colors!
If you have dress boots, you’re good. Some brands now have softer ankles but stiff outer panels above, so they’re stiff, but breaking them in won’t make your ankles bleed.
Black gloves can be used at the lower levels, but mostly everyone above 3rd uses white gloves.
After years of showing, I’m always a promoter of comfortable understated elegance. Keep the colors simple and you and your horse’s turnout neat. Pick clothing you will be comfortable riding in in either cold or warm weather. I have enough chrome on my horses that I don’t need a super blingy browband or helmet. I want my horse to be the center of the judge’s attention. And honestly no one cares what brand you’re wearing unless they like what you’re wearing and want to know what it is. I have found that everyone is very supportive at shows and we wish each other good luck or have a good ride as we pass by each other going into the ring.
But definitely check the attire rules and bits and equipment rules. If you have a specific question that’s not clearly covered in the rules, you can email USEF before your first show.