Word or a short phrase to describe a person who is socially responsible

Bob is a model citizen.

A "Model Citizen" is someone who obeys the law, is good to their community(s) and sets a good example for other citizens. not only citizens of a city or country.

Generally speaking, it is the role model of a group that conforms perfectly to the virtues and demands that any given society holds.

Robert Adams, Quora, Aug 15, 2015

It seems that you're looking for something that gives the opposite sense of superficial:

apparent rather than real; insubstantial or insignificant

Words that spring to mind are authentic, legitimate, and consistent.

If you want to use a more colloquial term, here are a couple:

the real deal: something or someone that is real or genuine : a thing or person that is not a copy or imitation

the genuine article: the real thing

Consider mensch:

A very sound, reliable, or honorable person; a person with great integrity or strength of character. From the Yiddish word mentsh, with spelling taken from the German word Mensch (human being).
Tom's a real mensch, always willing to help a friend in need no matter what.
_{The Free Dictionary by FARLEX}

I think a philanthropist, one who practices practices philanthropy fits the description quite well.

Philanthropy: altruistic concern for human welfare and advancement, usually manifested by donations of money, property, or work to needy persons, by endowment of institutions of learning and hospitals, and by generosity to other socially useful purposes.

Pillar of the Community

One who is a particularly active, respected, and influential member of one's local social sphere.

The Free Dictionary by Farlex

or Stand Up Guy

An honest and straightforward man of good character

Wiktionary

I get a feeling you're looking for an expression inline with civic duty.

There is also the expression social hero:

Social heroes differ from both martial and civil heroes in that their heroic acts do not necessarily involve an emergency situation. By sacrificing their time, finances and possible social status, social heroes work tirelessly to serve and foster their community and its values. Examples of social heroes includes volunteers, activists and whistleblowers. These individuals act with courage and kindness to promote an ideal, improve quality of life for others or to aid those who are struggling in their community. These types of heroes often perform their heroism regularly without asking for recognition or thanks, but their contributions are outstanding nonetheless. (source)

The phrase is used by official studies but is also quite popular on social media.

How about "Bob is a progressive"? Or "a progressive thinker"? It would cover a lot of bases from the socially responsible to the environmentally friendly.