Final Fantasy 14 has crossover events rather frequently, such as the recent Final Fantasy 16 event that saw Clive and Torgal arrive in Eorzea or the Fall Guys event that brought the frustratingly fun competition of not falling off the map to Warriors of Light everywhere. The nature of FFXIV’s world allows crossovers to be implemented rather easily and without needing extensive lore reasons to explain why characters from another world have appeared. Having multiple worlds exist in the universe of FFXIV opens the door to endless crossover potential.

https://screenrant.com/ffxiv-final-fantasy-7-crossover-event-unnecessary/