The impact should need to be material and related to some legal right you have, it seems to me. In general you cannot sue to enforce a contract or agreement you are not a party to, even if the outcome of adhering to that contract affects you.

That is the point: as a citizen in a city, you are part of that city and any contract the city is part of. Otherwise, what/who is a city?

In the US, normally, citizens of a city do not have the right to act on behalf of the city. They cannot sue on behalf of the city, they cannot unilaterally attempt to enforce the city’s laws, etc. There are some rare exceptions where cities and states pass laws that create private rights of action when regulations are violated but these are the exception.