Libre office draw is it good general purpose diagram application. I use it to draw all of my diagrams
To add to the other comment, the specific LibreOffice application that can edit PDFs is LibreOffice Draw. I've used this a couple of times when I got sent a (non-forms) PDF that I was supposed to print, fill in, sign, and then scan and send by email. It worked amazingly well for that!
LibreOffice Draw or Inkscape are the best ones that I can think of, but are not exactly ideal to replace Acrobat.
LibreOffice has a complex interface and may be difficult to use, while Inkscape is more of an Illustrator competitor, but can be used to edit PDFs.
Where can I get Libre Office Draw?
I found this link : https://www.libreoffice.org/discover/draw/
But when I want to download it, they say I have to download Libre Office, not libre office draw :/