On Day Zero only merit rules, not caste or community. Those who received good grades because they are intelligent and/or worked hard make the cut. Plus you need good communication skills. Remember Arjun Kapoor in Half Girlfriend: "I myself from village place?" Instant rejection.
Firms don't discriminate on basis of caste on Day 0. However, there is a sizable percentage of students from reserved category that come from marginalized communities, and they often don't have the requisite english speaking skills, social skills, contacts required for internships, quality laptops etc. which just closes many doors for them, including recruitment. Not saying this doesn't happen to general students, ofc its the same but percentage wise more people from reserved communities have this background.
IMO they solely care about batch ranks, nobody even asks about CLAT ranks (or i'd say even remembers the rank anymore).
Surprisingly I was asked about clat rank and I mentioned somewhere around 150ish. So do remember it anyway.