A group such as a group of friends, that an individual uses as a focal point in forming beliefs, attitudes, values, or behaviors is a group.

The term you are looking for is "reference group." A reference group is a social group that individuals look to for guidance when forming their beliefs, attitudes, values, or behaviors. These groups serve as a standard for evaluating one's own behavior or the behavior of others. Reference groups can influence a person directly or indirectly, and they may include family, friends, colleagues, or other social affiliations. For example, if someone is considering adopting a new fashion style, they might refer to the opinions and behaviors of their peers or a celebrity as a reference group to shape their own choices. Understanding reference groups is important in various fields, including marketing, psychology, and sociology, as it helps in understanding consumer behavior and social dynamics.