For my kids who have entered college with advanced standing, they didn’t do anything other than be themselves in middle and high school. They were taking advanced classes bc that was their normal progression. They have entered with anywhere from 20-59 credit hrs that transferred in as direct credit toward their degrees.
My oldest is a chemE and graduated in 4 yrs. He used 12 months within those 4 yrs to co-op, a good decision for employment. My other ds used it as an opportunity to grad courses as an UG and to spend more time in UG research. (He could have graduated easily in 2 yrs bc he has taken ~18 hrs/semester. He thought graduating early would hurt his grad applications due to more limited research. He has also used his UG yrs to discern the exact field he wants to pursue in grad school, something that at 19 he was not sure about and now as a college sr he feels confident about his decision.) My Dd is using it as an opportunity for double major plus minor and study abroad.