How much open loop gain can I expect from a plain no-frill opamp design? No-frill means, 3 pmos, 4/5 nmos, each w/l = 0.5/0.15 (bare minimum). No compensation circuit. Is it possible to achieve dc gain of 100DB?

I am no expert, but quickly throwing it in xschem, I'm more at like ~30 dB than 100 dB ...

Yes, I am also getting ~50db. So wanted to check in the community.

There are voltage amplifiers and operational amplifiers. A single stage voltage amplifier is not one, as it is not efficient for resistive feedback. A two-stage amplifier can reach 100 dB gain, if the transistor lengths are large enough, but not with the minimum length, as it is only reasonable for high speed circuits.

Can you upload a circuit diagram of a two stage opamp which can achieve a dc gain of100db

From a basic two stage OTA you will likely get ~60dB with good optimization. To get 100dB you will need much longer lengths, cascades, or gain boosting etc.

Rail-to-rail_inputoutput_bulk_driven_class_AB_oper.pdf

Thanks @Luis Henrique Rodovalho