The reason pdf documents are used is to protect the document from alteration. The same is for them to be scanned as jpeg( photo) A quick search online and a little bit of research will give you ways of protecting the document from alteration and allow it to be searched for words or phrases. Going on a course is not necessary just seek out some information. Googles great
Try this
Microsoft Word (Windows, Free if you have Word)
Open Microsoft Word (2013 or newer).
Drag and drop the scanned PDF into Word.
Word will convert the scanned PDF into editable text.
Save it as a PDF again (it will now be searchable).
courtesy chat GPT ( not tested)