SoFi actually has 4 NFL-quality locker rooms.
"SoFi Stadium boasts of separate Rams and Chargers home locker-rooms, two visiting NFL locker-rooms that can transform into four smaller locker-rooms for events like the Final Four (northside of stadium) and performer dressing areas on the venue’s southwest end. " [
ifollosports.com]
The Rams' locker room and the Chargers' locker room are on opposite sides of the field and the Rams 'home' side is opposite the Chargers' 'home' side. Network TV coverage is from the Chargers' side of the field, looking across the field to the Rams' bench. That is why the Rams' logo at mid field faces the visitor bench rather than the Rams' bench.
When the Rams and Chargers play each other next year it will be Charger home game, but each team gets to use their usual locker room and sit on their usual side of the field.
Since the Rams' and Chargers' locker rooms are custom built for each team I suspect that they will put the AFC champ into one of the visitor locker rooms and put the Rams in their own locker room. But in the unthinkable situation where the 49ers are in the SB I would bet that the two visitor locker rooms would be used.
AlbaNY_Ram