I got a stand up freezer today that is strictly for caking, but I’m unsure if it should be on the absolute coldest setting or in between? My current “food” deep freeze , which I was using as needed for cake items, is currently set between 5-6 with 7 being the coldest. I set my new one to the same and now I’m questioning my decision. lol. I couldn’t find anything in the search bar related to my question, so what do you recommend? 

That's probably a good place to start.  The only way to find the best setting is to use it.   The more you put into the fzr the(slightly) lower the temp setting needs be as the fzn items help keep it where it should be.   Do you want everything to be 'rock hard'? Or just fzn enough to be safe?   You can adjust as it fills up.

You should always have a thermometer in your freezer.  All of mine are set to maintain 0.