If it’s an item/object— wait it out. Put the link in a folder on your phone, and give it a few weeks. If you like it, you’ll still like it. If you like it in the context of a microtrend, or only in a photo with 10 other items, you’ll have more clarity.
If it’s a haircut/dye/change—look at as many photos of yourself, with as many haircuts, as possible, to get a sense of whether you like this in a general way or if you like it for yourself.
If it’s a hobby/activity/experience, go for it. Do it anyway, and even if you don’t love it or ultimately feel it was overhyped, you’ve done a new thing.