Speaking from experience, the "does this spark joy" thing works. Look at something and see if it brings you joy, if it has value for you by being here, and if it has enough value to beat its maintenance cost. The cost of owning something (cleaning it, finding shelf space or adding more storage space to your home for it, having to take it with you if you move, etc.) can be important, and it sounds like you are noticing now.

Also consider whether you are treating the object right. Things are meant to be used. I really like notebooks but I hate the idea of hoarding notebooks, because notebooks were designed to be written in, and I know from having filled over 60 journals now that a full notebook is so much more beautiful than a blank one. If an object is ignored, isn't being used at all, is it fulfilling its purpose? Wouldn't it be better off sold, donated, handed off to someone else who might actually use it?

This reminds me of a random Tumblr post about someone whose aunt passed away, and left behind tons of stuff that she kept for a more special occasion, like spices and fancy foods from past travels. It had sentimental value to her, but it doesn't to whoever inherits it. If you are putting off using some consumable thing for a special occasion, don't! Every day is a special occasion. That could let you get some use of the thing before, or instead of, throwing it away.

Before buying something, also consider whether the maintenance cost is worth both the price of the thing and the value you get from having it. Even if you throw stuff away, if you just keep acquiring more instead you're not going to get much of an improvement!

You can try to just sort through the stuff, just separating what you don't really like from what you like in a room. Make a random pile outside the room, then reorganize the rest of the room, and admire just how nice it is now. That can motivate you to throw it away.

If you think you are too attached to something to get rid of it, you can try just hiding it for a while, and when you get back to it see if you actually missed it. You probably didn't.

If you still can't bring yourself to throw something away, maybe donate it or sell it. But again, consider whether the time and effort spent doing that is really worth it, or if it's easier to just throw it away anyway. Even if it hurts in the present moment, it's probably better for the future you.