The strategy with small pairs is very dependent on stack sizes and also on positions and the general situation. Small pairs are generally bad
hands to 3-bet to a non all-in size, because they dont block any strong hands in our opponents range, and they play poorly postflop, when the stack to pot ratio is low. So if stacks are to deep to 3-bet all-in, we usually prefer to just call or sometimes fold a small pair, if someone else has already entered the pot. Because of the same rationale they are also hands, that we might choose to limp behind with rather than isolate the limper, especially if 2 or more people have already limped.