Insider tip
Set the PHP version per domain, not per account.
The CloudLinux PHP Selector in cPanel lets each domain on your account pick its own runtime, anywhere from 7.4 through 8.x. Pin a legacy app to 7.4 and run a fresh 8.3 project next to it without either one holding the other back. The same screen toggles individual extensions and tunes memory_limit, max_execution_time, and upload_max_filesize per domain.
Leave OPcache on (it is by default) so compiled bytecode stays warm in memory across requests, and use SSH for Composer and CLI PHP when you would rather manage dependencies from the shell. Stuck on an end-of-life branch? HardenedPHP keeps it patched against known CVEs while you plan the upgrade.