Try having the PDF OCRd (Optical Character Recognition/Recognised).
Good paid for PDF editors will have this built into the program to use and some free editors/viewers/readers may have the same. The results will vary though from good to bad, to doesn’t work.
It can also depend on the actual PDF and how it was created.
There are several on-line PDF OCR converters to use also (found by search engine), which if I’m honest, the one I randomly chose, performed far better than the OCR feature in Adobe Acrobat Pro DC which I tried first.

In my example below, I’ve used this PDF OCR converter - Free Online OCR - convert PDF to Word or Image to text - to recognise the text and convert to a .docx file.
The PDF used/uploaded is a magazine and I previously extracted a page to use rather than uploading the full PDF as size/page number restrictions may/will apply to free OCR converters.
I have also taken a screenshot of the page article in question and saved it as a JPG file as a comparison. This can also be uploaded and recognised and the result can have the text copied and pasted into a new Word page for easier reading/further copying in your preferred font.

Click the image below to see first a PDF magazine text selection being copied and pasted into a Word document. Result - squares as characters.
Then the single page PDF is uploaded on-line for OCR conversion. The result is downloaded and opened in Word. Result – reasonable conversion in default font with minimum/no editing needed.
Then the article (text) is captured via screenshot and then the JPG image is uploaded for conversion to the same on-line converter. Result – reasonable conversion, minimum/no editing.
Give it a try.