We didn’t think so with Farley
We picked up Farley, our wheaten terrier, when he was 8 weeks old. My sister-in-law picked up Piper, 8 week old border terrier, the same day.
On our 2 hour ride home, the pups decided to sleep together. Pretty cute. When they arrived home they were greeted by Murphy, a rottweiler, whose home they entered. Just to be on the safe side, we introduced the dogs outside. Poor Murphy was invaded by puppies for a week. Piper stayed with him, and Farley came home with us.
My only caution is not to leave the dogs alone when they are that young and new to each other. At one point, Farley grabbed Piper by the neck. Quick action by brother prevented any harm from being done, but it did remind us to be careful.
Now look how they get along. Farley looks like he wants to hold hand with Murphy . . .
How do you socialize your dog?