Hi npdynamite. Welcome to the forum
Personally I cant help you much, but Marko (the administrator of this forum) released a podcast on this topic a while ago. Although the information is a few years old, it is equally valid now. (although upsizing software should have improved in that time??)
Here is a link to the podcast episode How Big Can I print that Photo - Interview with Royce Howland | Photography.ca
Royce Howland who is interviewed by Marko in the podcast can be found here https://roycehowlandprintstudio.com/
Bookmarks