Happens a lot in FL. Even when I was in HS in the 90’s we had kids transfer in all the time. The team was ranked number 1 by USA Today my freshman-junior years. Each year 2-3 new studs would show up. We even had a UM commit from AZ come to the school for his senior year. A few years after I graduated they won the “national championship” with 6 seniors being drafted in the first couple rounds or something like that. Nowadays look at some of the power schools in the state. Look at their rosters year to year. Top ranked kids don’t all coincidentally move within their boundary for their junior and senior seasons.
In FL we have a choice program. As long as a school is not at capacity they can take kids from neighboring districts. If they are at capacity it is more difficult, but it can be done.
O.K., I never knew this type of thing existed...