The RCS value of MIUS to be measured will be smaller than Rafale, even with current body shape, internal weapon load capability and composite material used extensively in the hull. It is certain that even more effective results will be obtained when the RAM paint developed (I think Turkish paint will be far better than Have Glass V. Aselsan is working on those paints since decades) is also applied for MIUS.
The RCS value of the F16 has been reduced from 5m2 to 1.2m2 with Have Glass-V paint.
The targeted RCS value for TfX is between 0.1m2 and 0.003m2, depending on the angle of the aircraft. I expect a similar RCS value for MIUS.
The RCS value specified for KFX is 0.5m2 in open sources. The Su-57 is claimed to be in the 0.5-0.1m2 range. The RCS value of F35 stated in open sources is 0.005m2 and F22 is 0.0001m2.