It’s a really common problem.
My solution is to sort your wardrobe into right now clothes and everything else. Put the pressure to declutter or donate right out of your head because that interferes with the process.
But you do need to figure out somewhere to store the everything else section so that isn’t in your way. That could just be to the right hand side, or boxes on the top of the wardrobe.
Take each item and if it fits, it’s flattering, it’s seasonal and it suits the realities of your current lifestyle, it’s a right now item. But it cannot go back in the wardrobe unless you can find a whole outfit to wear with it.
This is usually where the problem is. The shoes with the perfect heel for those trousers wore out, and now they don’t quite work. Or you need a better bra for this top, or a racer back, or a wee vest. Make a list because this is what you need to spend your clothes budget on, not more clothes!
An other problem is that we buy an item, that looks amazing but it doesn’t quite go with anything. And fashion is crafty - this year’s green will be similar to last year’s but they will look wrong together. So you think something will work but it ends up being a singleton. This is something to be very vigilant about when you’re shopping. If it won’t function in an outfit, or you can’t afford the accessories, just put it back.
Once you have pared back to the clothes you could actually put on in the morning, you’re three quarters way to a functional and personalised capsule. And it is incredibly helpful to take the other clothes out of your visual field.
If I have clothes that need mending, altering or are missing a vital support piece (like the right bra) I turn the hanger backwards.