Welcome!
I have no idea how to purge. Today I’m wearing a pair of pants I got in high school or maybe early college. Used to wear them with yellow shoes but alas, I don’t have them any more. On top I’m wearing a sweater my son had to have several years ago that he later rejected. Teenagers!
While I don’t know how to purge, I have a few ideas on what to keep, (as long as you are not intent on always being abreast of trends and wearing the latest whatever):
Keep things you love, ideally things that make you smile when you put them on, but at very least things that feel like “home” (assuming home does not make you shudder or shriek).
Know your colors and keep to them even if someone else wears a really cool (on them) shade or stores are full of something that seems off when you put it on. If every item matches a central piece (=you), they will harmonize and you can mix them according to trending color schemes.
Go easy on all the trends. You can get a wildly swingy pair of pants, as long as they are the kind of icon you can pull out again down the road. If you get a whole closet full of them, then you’ll need a whole closet to store them in eventually. What works for me is to get quiet versions of trends I like, like my baby bootcut black jeans from the early 90s (like you, I’ve generally stayed the same size).
Shop your closet when you see trend reports. Figure out what the dominant feature or two are in a thing you like, then rummage through and see what you’ve got with those features, maybe in a different way than the thing on offer right now.
Take care of your stuff. If shoes can’t be salvaged, out they go. But have a good kit to take care of your stuff (I recently got good advice in a thread about a clothes care kit for my son. You can find members’ posts by clicking on the name).
Don’t worry about your style. If you keep everything in your comfort zone, it will eventually cohere.
Enjoy yourself, your family, your life. Don’t stress about your clothes: you can always change them.
ETA, dang, that’s good advice from April! Her 1 & eta are part of my initial K/R decision.