I have three Yorkie girls now, various ages and we want to get a male Yorkie pup and a Goldendoodle male pup. Will they fight for dominance down the line? I am worried about the male Yorkie.
It doesn't matter if you introduce a male or female dog do the family, the hierarchy will always be disturbed and reestablished.
Some dogs are more agressive, others timid while reestablishing the hierarchy. That's mostly influenced by their individual characters, but male dogs tend to be more dominant. That doesn't mean there are going to be physical fights among your dogs. On the other hand, if 2 dominant females are introduced to ech other, they can fight just as fiercely as males.
In general, pups will behave submissive until they reach sexual maturity. If you don't want to breed them, that's also the time to desex / neuter your male, which has the tendency to make him less dominant.
To avoid physical fights among your dogs, you should be the most dominant pack member and keep the atmosphere friendly between all dogs. If your current dogs are obedient and follow your command, and you feel confident to train and care for the new pups just as well, go for it. If your dogs often do things you don't actually want but you feel like you cannot control them, adding more dogs will only make the problem worse. In that case I would advise you to reconsider.