It does not translate as sexist, but respectful. However, many women see it as sexist these days, especially from the USA. Even so, people with invisible disabilities really appreciate the gesture....such as chronic fatigue or such. There is a way to avoid giving offence. You could say: "Excuse me, I am getting off soon. Would you like my seat?"Then you move away as if you were going to do just that, even if your stop is distant.

I think it's rather sexist and telling someone that they look tired is rude.

US: It's common for people (both men and women) to give up their seats for people (both men and women) with disabilities, or who are struggling with their footing, or have too many packages, or pregnant (just women, not men). It's a courtesy to help out someone who needs help, no matter what gender you or they are.

Hello Rook! In my country, it is generally considered very polite and kind to give up your seat for a woman or an older person. This type of courtesy is becoming less common, though and because of this reason, people don't always accept this type of courtesy graciously. And then, of course, you also have people that bring up their children without these "social graces". I hope that helps!

Just ask. If they say no, continue on your way. If they say yes, you can give it up.