If you only see one resolution that is smaller than you expect (as you say "everything looks scaled up a lot"), this usually means the system is using an unaccelerated firmware default resolution as a fall-back.
On x86 systems with legacy BIOS firmware, this usually means the system is using basic VESA SVGA display modes. On systems with UEFI, this means the system is using the
efifb driver, which provides a very basic unaccelerated framebuffer graphical display with just one or very few resolutions available.
To fix this, more information on your hardware is needed. Mainly, what GPU(s) does your system have? Manufacturer and model? What does
lspci -d ::0300 -nnv say?
Based on this information, we could then figure out if the GPU is supported by open-source drivers available in the distribution (in Debian, this would be the optimal situation), or if you need proprietary drivers or just a newer driver version from Debian Backports.
In the simplest case, you might just need to tell the package manager to install the correct
xserver-xorg-video-* package for your hardware:
xserver-xorg-video-amdgpu for modern AMD Radeon GPUs
xserver-xorg-video-nouveau for essentially all but the latest NVidia GPUs
xserver-xorg-video-intel for Intel iGPUs
There are other options, but these three are probably the most common ones.
If your system is a modern laptop, it probably has two GPUs: a low-power CPU-integrated iGPU, and a more powerful discrete GPU chip to be used when high graphics performance is needed and/or you're not on battery power. You'll need drivers for both GPUs.
Please edit your question to add the output of the
lspci -d ::0300 -nnv command. After that, either me or someone else can provide you with specific instructions.