Apex Legends introduced cross-platform play in October 2020, and the game has been better off for it. Queues are faster, and playing the game became simply more accessible.
PlayStation 4 and Xbox One players have been put in the same lobbies, with PC players remaining separate. The only way a player on console can play in PC lobbies is if they party up together. The console cross-play feature can be turned off, ensuring that you can only play against people with the same console as you.
Voice chat works across all supported platforms, so you can talk to your teammates even if they're playing from different devices.
Adding your friends on other platforms is simple. Navigate to the Friends menu, then select "Find Friend." Next, search for the username you wish to add, then send a request. Once a part of your friends list, you can jump in and out of any lobbies with your cross-platform friend just as you would with someone on your native console.
When filling out squads, if there's a PC player in the lobby, PC players will be filled. If you need a fill player and both players are on console, a console player will be filled.