We had a 2007 rear kitchen Outback fiver that had a range hood with fan but it was not vented to the outside. I took care of that!
It was a really simple mod to do. Just use a stud finder to make sure there are no wall studs right where the vent needs to go through the wall.
If your existing range hood has the fan but not vented all you need is some simple metal duct work to go thru the wall and cut the knock out of the existing hood. Of course, you'll need the exterior vent of which there are a few to choose from.
If you have to buy a new hood, there will be a few of those to choose from, too. I doubt any o them will come with the exterior vent. Don't forgot to seal up the duct work in the wall and caulk the exterior vent. Good luck.
2018 GMC Sierra 3500 DRW 4x4 Duramax/Allison
2014 Lifestyle LS36FW
St Augustine, FL