India doesn't have a 2 party system (I don't think?). If you look at the seats in parliament there is much more of a rainbow which suggests it is more democratic than the US. Maybe it will eventually evolve into a 2 party equilibrium as more people vote only for bigger parties they think stand a chance, rather than for ones they actually believe in (practically mathematically guaranteed to happen if India's political system has no defence against the spoiler effect). But that shift will take time. If I am right India will eventually be hyper-polarized like the US after it "2-party-crystallizes."
If there were only 2 viable political parties in India right now where votes were split near 50-50 each election cycle and each party viewed the other as a huge threat and amplified how terrible the other is on social media 24/7 I think we'd see cultural norms shift in India and people would start to become more quiet on politics. Population density I don't think would be that key a factor.
Likewise, if the US had multiple political parties all represented in parliament and there just wouldn't be as much political hyper-polarization and without 2 parties tribalistically fighting winner-takes-all style it is much easier to have cultural norms that you can talk controversial political stuff