https://ourworldindata.org/future-population-growth
(Obviously, the error bars for a prediction like that are large.)
Many developed countries are already losing population:
https://www.worlddata.info/populationgrowth.php
An even larger fraction of developed countries would be losing population already if it wasn't for immigration. This suggests that as the developing world becomes more like the developed world, human population will be less of a concern for the global environment.
My perhaps radical position is that two best solutions for surviving climate change are birth control and education for women. The fewer people we need to keep alive, the more easily we'll be able to adapt to the changing climate.