Some explicit online games may be rated "AO" (stands for Adult Only), determining games that have content suitable for only Grownups in excess of the age of 18. Also, online games need to also have an ESRB see that warns that any "online interactions are not rated through the ESRB". https://ce-air7.com/why-cross-platform-play-is-crucial-for-the-future-of-online-games/