There are many reasons to not use auto iso, in spite of the fact that modern sensors produce much less digital noise than they used to. If you're enlarging your images, or cropping significantly, you'll want images that are as clean as possible. It also tends to vary from camera to camera.

For sure, on my D850 (and anything from that era I suppose), I can set the ISO range (minimum and maximum) and the minimum shutter speed (if using A or P mode).