I wanted to ask if there's a possibility that I can plug my XBOX into the PC so that the PC then transmits it to the screen
Ehmm yes, just right into the screen
Yes the screen has vga and i have no adapter there
Then you have to buy one. There's really no other way. At least not without a lot of delay and so on.
This will not work with a VGA adapter the Xbox is not able to send analog signals via HDMI
It is already clear that hardly any device can do that today. Of course, you have to buy a converter. It doesn't make much sense anyway.