DR Tibor,
if you tried DOSBOX emulator in WIN environment, MAC OS, LINUX, etc…, so you will elegantly set the problems with graphics and the size of the DOS window in the dosbox configuration file-0.74.conf in the SDL section, for example, as follows
fullscreen=true
fullresolution=original
windowresolution=1024×768
output=opengl
73, OM5NA rain