DOOM 3 (2004): autoexec.cfg

com_allowconsole 1

seta r_mode -1
seta r_aspectRatio 1 //(0 = 4:3, 1 = 16:9, 2 = 16:10)
seta r_customHeight 1080 //(Your screen height)
seta r_customWidth 1920 //(Your screen width)