Legacy can be a tradition you start: Sunday pancakes, a yearly road trip, a family taco night.

Traditions are just things somebody did twice on purpose. Every family ritual you can name was invented by a person at some point, usually with no sense of founding anything, and it became permanent only because it got repeated until people expected it. Which means the job of starting one is open, and at your age nobody else has claimed it. The barrier is mostly that it does not occur to anyone that it is theirs to do.

Pick something small and cheap and do it on the same day twice. Pancakes, a walk, a film in December. Say when the next one is before anybody leaves the table.