The resolution is irrelivant, it's the recording data bitrate which effects the storage capacity, as also the i-frame and b-frame and frame-rate settings.
Also most CCTV system have a quality settings, which effects also the compression, persume the devices are in H.265
Also Linus mentioned" motion detection", using that even with a pre/post recording saves a massive amount of space.
Fair to say as long as he masks the trees on the software, the amount of recorded data during a 24hour period is very minimal, in a surburbon area.