For something on the smart casual end, wear a grey cardigan and a white long sleeve shirt. This ensemble demonstrates that staying fashionable as a gentleman over 50 is totally doable.
White Long Sleeve Shirt with Grey Cardigan Outfits For Men After 50
This combination of a grey cardigan and a white long sleeve shirt looks amazing, but it's super easy to throw together too. Introduce a pair of tan leather double monks to this look for an instant dressy look. The ability to pull off combos like this is one of the advantages of being middle-aged.