This page is our investigation of cross-play feature in game called Apex Legends. We also want to mention that - we always put manual efforts to find the precise, valid, and what is more important official information about different game features without using AI.
Yes, Apex Legends has full cross-play support; players on PlayStation 5, PlayStation 4, Xbox X|S, Xbox One, Nintendo Switch, and PC (via Steam, EA App) can play together.
This information is taken from the official EA help center, which you can check for yourself by following this link.

Apex Legends received cross-play support on October 6, 2020, with the start of a new season called "Aftermarket".
Games can have different cross-play combinations, for example the game can have cross-play between PC, Playstation 5, Xbox X|S, but not between old generations like: Xbox One, Playstation 4, PC. To avoid any misinterpretations, we group them into so called "cross-play variations".
Any store inside the cross-play variation have a cross-play only with a store in the SAME variation. We also want to notice, that we put into variation not platform, but store + platform. That is required because some games, for example, can have cross-play between a Playstation 5 and Steam, but not Playstation 5 and Epic Games.