Fujifilm X-T30 II has a
26.0MP APS-C (23.5 x 15.6 mm ) sized X-Trans CMOS sensor and features X-Processor 4 processor. On the other hand, Pentax K-3 II has a
24.0MP APS-C (23.5 x 15.6 mm ) sized CMOS sensor and features Prime III processor.
Another similarity between these two cameras is that both Pentax K-3 II and Fujifilm X-T30 II sensors lack anti-alias (Low-Pass) filters. Removing anti-alias filter increases the sharpness and level of detail but at the same time, it increases the chance of moiré occurring in certain scenes.
Below you can see the X-T30 II and K-3 II sensor size comparison.
Fujifilm X-T30 II and Pentax K-3 II have the same sensor sizes so they will provide same level of control over the depth of field when used with same focal length and aperture. On the other hand, since Pentax K-3 II has 7% larger pixel area (15.24µm2 vs 14.12µm2) compared to Fujifilm X-T30 II, it has larger pixel area to collect light hence potential to have less noise in low light / High ISO images.