However it will come with great pain for the vast majority.
India is politically reverse of the US. More populated states like UP have more representatives, they are usually conservative (nationalist/right wing) in politics, lesser education, lesser efforts in family planning etc.
There has not been redistricting called delimitation commission in India since 1976 on some of these population growth concerns, it is currently scheduled for 2026.
The TFR in most parts of india is below 2 these days, but the most populous states are still growing , that make the national average.
It is hard to win an national election even today without UP.
However they have other very large islands (Sumatra, and part of Borneo) that could be settled, so it's not an insurmountable problem.
China's and India's large populations are their Achilles heels - they need vast quantities of food and water, yet China imports 50% of some food items, and India relies on Himalayan headwaters that China is diverting.
In the early millennium, while traveling for several months in India and being shocked at the situation in states like Uttar Pradesh, I would occasionally ask Indians I met if overpopulation was not seen as a problem. The response was often that India’s mighty population is what will let it throw its weight around globally in the 21st century, and claims that India is overpopulated are a Chinese or Pakistani (or both) plot.
I wonder if this belief has only strengthened with the more nationalist government in recent years, and the even greater tension with China.