What would you suggest as ways for a city like Detroit (or Pittsburgh) to fight against, but also to successfully manage population decline?

If you live in Philadelphia, you are no longer living in a shrinking city, at least according to the 2020 Census, which indicates the population grew by more than 5% since 2010. But this was the first census to mark growth since 1950 and since then the city has lost almost 25% of its peak population.

City shrinkage can feel apocalyptic, as in the case of Detroit or in Halle, Germany. But what might be some up sides to the phenomenon? And what would you suggest as ways for a city like Detroit (or Pittsburgh) to fight against, but also to successfully manage population decline?