virtualbox.org

I am a noob at this, but still I need help, I have already installed the Virtual Box Guest Additions and it worked, it was in full screen (the wallpaper) other than that, it's all in the same size, the start button is small, the taskbar is small, the icons are small and even if I open file exporer, it still small as it is, how can I fix this please help.

XP predates 4K displays, it simply doesn't have toolbar graphics and icons designed for 144dpi.

I have fond memories of XP, but the blunt truth is this: if you want modern graphics capabilities, use a modern OS, not one that is now 20 years old.

That said, I get the best results by selecting a lower resolution in XP using one of the View|Virtual screen 1|Resize to www x hhh settings. Then in the same menu, enable the 200% scaling option. The "lower resolution" has to be chosen so that doubling it will result in a window that still fits your monitor. The 200% option is best because it is an integer doubling of the pixels - non-integer scaling IMV leads to too much blur.

The 200% scaling feature seems to work with fullscreen mode too: VirtualBox will automatically choose the largest half-size resolution that fits. However I do not find fullscreen mode to be useful (I like to move the mouse between host and guest), so I have not used fullscreen mode a lot.