There’s a reason why people are generally not doing scientific computing, machine learning, hardware integration, systems programming, etc. in PHP (yes, there are likely some obscure projects doing all of those, but in general, it’s not done because of limitations in the PHP runtime).
If you already know PHP, you can probably have a long and healthy career in that space. But if you’re new to programming, you’ll probably be better off learning Python or Rust, or maybe one of the platform-oriented languages like C#, Kotlin or Swift. JavaScript is also a very popular choice, because it’s currently the only thing you can easily use in the browser, but that might change with the rise of WASM.