Diablo IV supports crossplay as you will be play with others on other platforms. To see how you can enable or disable this feature, you can take a look at this tutorial from Seeking Tech.
1. For the first step, you need to enter the Options menu.
You can do so from the main menu by pressing the Options button on PlayStation gamepad or Menu button on Xbox controller.
If you are currently playing the game, then you can press the touchpad on PlayStation or View button on Xbox to open the Map Screen. From there, use the L1/R1 buttons or LB/RB buttons to switch over to the Game tab. Afterwards, select Options.
2. Once you get to the Options menu, use the same L1/R1 or LB/RB buttons until you get to the Social tab.
3. From the Social tab, you should see the Cross-Network Play setting from the Cross Network section located at the top. This should have the following description:
Enabled: You will encounter and be able to play with players on other platforms.
Disabled: You will no longer encounter or be able to interact with players on other platform. Clan feature will become blocked.
If you want to turn on cross-play, you need to make sure that the Cross-Network Play setting is selected. Furthermore, you need to link your PlayStation Network or Xbox Live account with your Blizzard.net account if you haven’t done so already.
If you want to disable playing with other platforms, then you need to make sure that the Cross-Network Play setting is not selected.
3. In the same Cross Network section, you will also find the Cross-Network Communication setting, which has the following description:
Enabled: You will be able to text and voice chat with players on other platforms.
Disabled: You will no longer be able to text or voice chat with players on other platforms.
If you want to enable cross-play as well as cross-chat, then make sure you have this setting selected. If you want to keep cross-play but disable cross communication between different platforms, then you need to make sure that this setting is not selected.
5. Once you are done making the changes, press the Triangle button on PlayStation or Y button on Xbox in order to save and apply your matchmaking preferences.
Cross-platform play in Diablo 4 can be done between PC, PlayStation 4, PlayStation 4 Pro, PlayStation 5, PlayStation 5 Digital Edition, Xbox One, Xbox One S, Xbox One X, Xbox Series S and Xbox Series X players.