Yes, socialization of your puppy with strangers (men, women, children of all ages), in the car, at the vet, with you wearing sunglasses (yes you wearing sunglasses), the list goes on, is incredibly important in the first 4 months. More specifically from week 8 to week 12.
Weeks 8 to 12 are when they absorbing all of the experiencing, being curious and going through their habituation. This period is when they are most “open” to all different kinds of experiences. After 5 months, it becomes more difficult to get them to be open to lets say a bearded man if they never met a bearded man before. It can be possible for them to fear them. Some people may think the family and multiple dogs in one house is enough socialization but the more socialization a dog gets, the more open they will be. Remember there is no such thing as too much socialization and will probably be the best investment you will make in your puppy to avoid future fears or issues.