Are multiplayer games designed for different platforms?

I don't know about gaming. There are many games that can be played online in multiplayer mode against other players. But are the games always tailored to the respective platform? So can Playstation gamers only play against other Playstation gamers, or can XBox users also play against Playstation gamers (assuming it is of course the same game)?

It depends on the game, Fortnite, for example, offers a cross platform, i.e. Android, iOS, Windows, PlayStation and XBox can play together.

Call of duty, dead by daylight

This is different for every game. Even on the PC sometimes not everyone can work together, e.g. This is often the case with ports from Ferral, so that GNU / Linux and macOS users can play with each other without any problems, but Windows users can only play with other Windows users.

I do not know DBD, there's probably no cross platform at COD, it is best to inform yourself.

Yes, I can imagine that the games are not exactly the same on the different platforms.

The newest COD MW has crossolatform support (so far the only COD that supports this), at DBD I don't know, but in general you can do this your game title and then crossplay Googln, for the future 😊