If I factory reset my iPod touch, will it automatically update to the most recent iOS?

I have a really old iPod Touch (6th gen) and I'd like to do a total reset so I can give it to my grandfather, whose computer can only run an older version of iTunes (not sure why). He tried with a different device before, but it was too up-to-date and wasn't compatible with his computer. So, my concern is: if I factory reset my device, will it automatically update to the most recent iOS? Or, at least, the most recent one it can handle?

[Re-Titled by Moderator]