Daughters are 23 and 20. Usually with the older one (1 hour away) we have taken her out to supper on or near the day. The younger one is 2 hours away and her birthday is very close to the start of the school year, so we’ve only gone down for one of three college birthdays. This year we bought her a TV in the summer for her apartment and said this is your birthday… If she lives closer after college we’ll probably do supper each year if possible.
When they are married/with families that might change. I think my parents just sent a card with money after I wasn’t living with them.