Both Fujifilm X-T30 II and Fujifilm X-T30 III have APS-C sized 26.0 MP resolution sensors so sensor size and resolution is not a differentiator between these two cameras.
Another similarity between these two cameras is that both Fujifilm X-T30 III 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 X-T30 III sensor size comparison.
Sensor Size and Resolution Comparison image of Fujifilm X-T30 II and Fujifilm X-T30 III Cameras
Fujifilm X-T30 II and Fujifilm X-T30 III 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.
Sensor size sets the circle of confusion, so it drives how much depth of field each
of these bodies gives you at a given aperture. You can calculate it exactly for the
Fujifilm X-T30 II
or the
Fujifilm X-T30 III ,
including hyperfocal distance.