Can use cvt to calculate the values and provide them to xrandr
cvt 1600 900 60
Or just copy paste this for 1600x900
sudo xrandr --newmode "1600x900_60.00" 118.25 1600 1696 1856 2112 900 903 908 934 -hsync +vsync
sudo xrandr --addmode eDP-1 1600x900_60.00