Totally only upgrade if you truly need to for reasons you can’t live with. In my case hiking and off roading makes satellite sos a must in case of catastrophic event that hopefully never happens.Just swap the battery for a new one if you are still into upgrading. Mine is 80% now too (11 Pro) but I have 3 powerbanks around so I basically never feel that I am out of juice.
New iPhones won’t make you happier since there are basically not so many new features in regular 16 (which is hideous IMO) or 16e