Population growth is at an ever decreasing rate. We are very near the plateau and many countries, like Japan are on an actual decline.
Global decline will occur before the end of this century.
Faster than that. We are already well below 2.1 babies per woman (steady-state population), but there are enough young women that the world population will peak between 2032 and 2042, assuming no increase in war, plague, famine, or pestilence. So, say 2032, at 8.4 billion.
The decrease will start slowly at first, but will accelerate as fewer women become fertile, while more hit menopause. By 2050, the average will look like these States. By 2062, the world will look like Japan with twice as many deaths as births. That will be roughly 100 million deaths and 50 million births. Average decrease 2032-2062 will be about 18 million per year, so from 8.4 billion to 7.86 billion.
At some point, births will stabilize. If at 50 million per year, with life expectancy of 80 year, then population stabilizes at about 4 billion. However, the distribution will be vastly different, and larger wars will intervene (probability > 99%).
For example, at current trends, the population of Japan in 2100 will be less than 20 million, and more than half of the population will be over 60 years old. Chinese, Indians, Indonesians, or Filipinos will invade, and Japanese culture will be wiped out. Repeat for South Korea, Italy, Greece. First, one country at a time, then entire regions. Demographics is destiny.