>>3140409>What is that option called and where can I find it in the menu?I guess you're just not familiar with your camera.
On my A7ii, I go into the Cogwheel menu -> page 6 -> Custom Key Settings -> Page 2.
From there I just configure the "AEL button" to
AEL Toggle
The icon is the Center spot metering.
It's a fantastic feature, since I simply point the center of the camera to the sky or highlights, engage the EAL toggle with a single click, then recompose, and recover the shadows in Capture One.
The only thing I adjust is the Aperture and ISO.
The Shutter Speed is handled by that Spot metering. 