Yeah in PHP, unless you have some opcode caching that ignores file modification time, you simply need to just change the file and it immediately starts running the new code. There isn't a compiled runtime generally that persists across requests. This is one of the great things about php, and is one of the things that made PHP so pervasive and get the marketshare that it did.

When I last did PHP, i ran it all in docker, but the same thing applies.