Adding a 3rd dog

Hello! So I have a 2 year old neutered Goldendoodle that is very mellow loves everyone. Then I also have a male Saint Bernard that is 9 months old. The saint loves everyone also. He's pretty mellow also never had an issue with the dogs together. I really like male dogs vs female dogs. So who has 3 large male dogs together? Thinking about adding a Great Dane or another Saint Bernard in about a year or so. Prefer to have another male. Please let know your experience with having more than one male in the house hold.
Thank you.