Sports venues located throughout the GTA 6 map. Related article: the Vice City stadium piece.
Confirmed sports venues
The Vice City stadium has its own page. No other named stadiums or arenas are confirmed yet.
Plausible additional venues
Real Miami has Hard Rock Stadium, Loan Depot Park and Kaseya Center. A city as large as Vice City could plausibly have more than one stadium-level venue. Speculative.