There is no going back, so consider what features are in iOS 26 that you will use regularly. Is there something you see as truly beneficial or do you just have FOMO because there is a new OS with a new look? Go to an Apple Store or Best Buy and play with a phone running iOS 26 for a good long while and make sure there are no concerns about Liquid Glass before making a decision.
There has been coverage that iOS 26 uses more battery than iOS 18. And if you have to reduce transparency to make the phone more accessible for you, that will provide an even bigger battery hit. Since you said you are on a 3-year old phone, are you still on your original battery? Are you well above 80% battery health? From what I've seen, the slowdowns for low health make iOS 26 pretty painful to use, but if you have recently replaced your battery then it should perform reasonably well. (My wife has a 14 Pro with 79% health. We downgraded it back to 18.7 during the beta cycle for this reason.)
