If you install LiteSpeed Web Server to cPanel EasyApache 4 through the LiteSpeed auto-installer script, there is no extra requirement to configure PHP for LSWS. LSWS should work right out of the box.
For LSWS v5.2.x and lower, the LiteSpeed auto-installer script will add the necessary external apps and script handlers automatically.
For LSWS v5.3 and above, external apps and script handlers are no longer necessary, as they have been built into LSWS itself. Specifically configured external apps and script handlers, however, can override the default settings. Please check this wiki to understand LSWS PHP auto-configuration feature.
If you are using cPanel EasyApache 4 with CloudLinux, LSWS should work right out of the box as well for most of the situation. If you have some special requirement about PHP configuration, you can refer to this wiki to learn how to configure LSWS to use either EA-PHPxx or Alt-phpxx. Most of the time, LSWS will honor whatever PHP binary and version you set to Apache.