Panasonic LX100 II has a 17.0MP Four Thirds (17.3 x 13 mm ) sized CMOS sensor and features Venus Engine processor. On the other hand, Panasonic LX100 has a 13.0MP Four Thirds (17.3 x 13 mm ) sized CMOS sensor and features Venus Engine processor.
Below you can see the LX100 II and LX100 sensor size comparison.
Panasonic LX100 II and Panasonic LX100 have 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 Panasonic LX100 has 32% larger pixel area (17.71µm2 vs 13.37µm2) compared to Panasonic LX100 II, it has larger pixel area to collect light hence potential to have less noise in low light / High ISO images.