Ideally you want your population to contract, while you increase per capita well-being through productivity gains. Each person gains, while the society eases up on the pressure it exerts via resource demands. There are few exceptions, perhaps countries like Estonia which are already tiny and still contracting (where a stable population might be preferable).
Adding people is one of the worst things most nations can be doing at this moment in history. Overall economic growth (almost always the argument used to push for expanding population at any cost) is not inherently valuable, it's the per capita growth that is the best measure. You want greater output per capita and to accomplish it using fewer resources.
Just ask France and the UK. They've added 10 million people to their collective population since 2006. They've produced zero per capita economic growth in all that time. Their citizens are wildly unhappy about what's going on as one would expect. The elites have done well, while most people have seen their wages and standards of living stagnate for decades. That path isn't going to sustain much longer given the current climate. It's going to require a refocusing on per capita well-being, instead of trying to grow the overall economy at any cost. Most developed nations, including the US, are in the same boat.