Welcome
I shoot with a D610 and try to max out my ISO at 2200 rarely going to 3200. It will shoot higher but I like to keep to those "lower" ISO's.
And as has been said when it is necessary to bump up the ISO to higher levels much can be done in post with software. That is an option.
The other approach is to use speedlights (flashes). They offer so much, but do get the flash off the camera. But that is a whole other story.