Despite all the talk about full-frame mirrorless cameras lately, APS-C is still extremely important for Sony. The A6000 in particular was a huge hit, thanks to the combination of good performance, features, compact size and price.
The 24.2-megapixel A6100 has the difficult job of replacing that classic, which came out way back in 2014. At that time, very few cameras could compete with Sony, but in 2020, the A6100 has some serious rivals, especially APS-C models from Canon and Fujifilm.
Sony has gradually refreshed its APS-C lineup, with the A6100 the last model to come, following the A6400 and A6600 -- neither of which I was terribly impressed with. Both have world-class autofocus systems but otherwise failed to keep up with rivals. At prices as low as $600, however, the A6100 has wider market appeal and less competition.