I think it is very individual. For example many women find hrt makes them gain weight, which can be very ageing, if it’s tummy and boobs, others may feel a lot better and due to that have a healthier lifestyle, thus making them look better.
i also don’t think anyone necessarily looks younger or older, i think everyine looks within 5 years of their age, it is just how good you look for your age, and for me that’s about how healthy you look. So younger and older are likely the wrong words.
healthy looking hair, healthy glowy skin, a toned body, good clothes thay fit,are well laundered and fresh, are current and are of good quality all give a more youthful appearance,
where as dull hair needing a cut or a colour if coloured,, dull dry skin, a flabby body with a big belly and matronly bust, poor clothing choices, ie Ill fitting, poor quality, not well laundered and fresh looking, dated, can be very ageing when put all together.
so for me, it’s not one thing, its not take hrt and it knocks the years off, or be a healthy weight, it is a much wider set of criteria that dictates how good or less good we look as we age.