[tde-users] Set resolution *before* login

Hello all, I'm setting up a laptop with a 4K screen (it's a Thinkpad P51). This 4K screen will be used to manipulate Photos (with programs that require Windows...). I have installed Linux as well (for everything that does not require M$ stuff) with MX-Linux and TDE. I want to run TDE (and mostly all Linux programs) at 1920x1080. I've managed to do this with xrandr, running from a script that is in /usr/local/share. The last "problem" (with which I can live, just nags me) is that this script visibly is run relatively late, after the login screen, which is then tiny. I first set it up for xfce/lightdm and the scripts are triggered from *.desktop files in ~/.config/autostart. I found an /opt/trinity/share/autostart and hoped it might run thing before login but it does not seem to (or more probably my syntax is not the right one). So the question is: is it possible to set resolution before login, if so how. I'd prefet to continue working with xrandr than hardwiring something in the X configuration file. Thierry