I'm not sure if this is an actual problem or just me misunderstanding how screens/resolutions work.

My issue is this; whenever I watch movies, series or just YouTube, quite often it's at this really small rectangular resolution with black boxes all around. This will also occur in video players such as MPV and VLC when watching latest season Andor for example. However, it does not happen on all videos - which is why im confused regarding this.

My screen is an Alienware 34 Curved QD-OLED Monitor - AW3423DWF.

Is there a way I can scale the resolution up?

Let me know if I can supply any additional details and thanks for any help!