I use Emacs as editor, but in my new laptop it opens always fullscreen and maximized. I tried everything suggested in this thread:

https://superuser.com/questions/124891/emacs-starting-maximised

but nothing  worked. The laptop has a very high resolution screen, I run it with a  3840x2160 (16:9) resolution and 2.12 scale, and so emacs thinks it would go over the screen and starts maximized no matter what.

I could finally find out how to do it. I actually am starting emacs with this alias:

emacsclient --alternate-editor="" -c

Adding the following lines to my emacs start file (.emacs) solved it:

 (add-to-list 'default-frame-alist '(width  . 20))

 (add-to-list 'default-frame-alist '(height . 10))