PS4 Custom Button Assignments

The PS5 also has the same ability as the PS4 here. Minus the short cut "Enable" in the ps button menus.

The PlayStation 4 has built in "custom button assignments" in its menu options. Useful in shooters when "Run" is set to the L3 by default and with this feature you can set R2 to be X in a game that involves Tap X to run or jump.

If you go all the way to the right in the top menu is "Settings" and then "Accessibility" then "Custom Buttons Assignment," and when playing a game or anytime, you can press the PS button on the controller and hold it down to open a mini side menu and within that you turn on or off custom button assignments. You can also add or limit what is in that PS button menu so you don't have to scroll so much to navigate to the custom buttons on or off option.

1.) Go to the right in the PS4 main menu in the top XMB bar options go to the white tool box icon it's called "Settings."
2.) Go to "Accessibility."
3.) Go to "Custom Buttons Assignments."
4.) After you set the buttons, in the previous menu select "Enable." A check mark appears.
See image below. The same "Enable" function is in the ps controller button in the middle if you hold it down, a side menu opens, you can turn on / off buttons.