PDFs are absolutely editable, but usually you need paid application for that. Thanks to some dumbassery in my previous job, I had to use the paid version of Adobe because I regularly had to edit PDFs. There are some security options that can make PDFs more challenging to edit, even with the paid tools, but I've always found ways around those too, usually by simply using "Print to PDF", then editing the output file.

Isn’t is possible to send a Word doc in read only mode? I’ve been sending mine PDF as I search recently but some companies do require a docx or at least have in the past