By no metric is this Asia's biggest. It is not even close to being even India's biggest. Even when all phases are completely built out (with a very generous 2040++ timeline), this will still be smaller than other proposed airport terminals like Guangzhou and Istanbul after expansions
Ya'll Nibbiars
1 . The BDIA is planned to have capacity of 15 Crore + by this devade itself.
2 . The KSIA will have a capacity of 20 Crore + by 2040's.
3 . The haneda is mulling for a Intergated terminal to replace the order one. So it will become even larger, may be 15 crore + or even larger.
4 . The Changi Airport will see another expansion making 12 crore + by 2030's.
5 . The LAX will reach 12 Crore + by early 2030's.
6 . The JFK will also reach 12 crore + by mid 2030's.
7 . The New Saigaon Airport will reach 12 Crore + by 2040's.
8 . The Soekarno Hatta will reach 12 crore + by late 2030's
9 . The Duabi will easily do that in this decade,
9 . The Dallas will also by thir or next one,
10 . And so will the O'Hara bybthis devade itself,
20 . The Istanbul by 2030's depsite all the country's problems,
21 . The Pudong also by the next decade fir isre.
22 . The Shenzen will recah 15 Crore + by mid 2030's eaaily.
23 . The Gunzhao will also easily by this decade itself.
24 . The Dailan will also have similar capacity by the 2030's itself.
25 . The Frankfurt can also.
26 . The by this devade likely as they alreday have that capability and capacity.
and other will reach similar capacity by the 2030's.
So this notion of the NIA being largest in the world or Asia is optics and nothing else.
Many large airports will be completed by then and by that time the NIA may not even be in the top 30 any likely.
And that's why Mumbai is going for a Third Airport the NYC way.