I do know a little of something about this since I’m starting to show some wrinkles due to aging. Personally I think it’s best to cover up somewhat rather than show your age by exposing everything by wearing tank tops/camis out in public when you are in your 70’s. 🙄
I would stay away from layering a cardigan over another short sleeved top - too hot!!
What I do now is find tops that are styled with loose arm designs - nothing tight from shoulder to elbow (or below). That gives your arms freedom of movement and AIR! (some people refer to them as having bar-wing styling; it can be a very attractive fit for many women.) Your neckline styling can be scooped, v-necked, etc. Lightweight summer fabric. No two layers!! Cool 😎
These cute summer tops are out there. Give it a try and don’t be sweaty.