The focus hold button has been the obvious choice for Eye AF in the past. But with the introduction of Sony's continuous Eye AF in 2019, it's become mostly irrelevant.

There's an aperture priority mode which was introduced in the third iteration of full-frame Sonys. This super aperture priority mode really takes this semi-automatic mode to the next level. It's also a must if you shoot street photography. Here's a quick set-up guide.