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From schematic, If possible, use larger size transistor, pay attention to the bias current ratio between first and second stage.
From layout, unit matching, common-centroid, dummy devices, the same current direction in the matching pairs would be better.
surely making devices bigger will reduce your offset, but you should also pay more power if you want to maintain other parameters like Gain and GBW the same.
Other than scaling, some circuit techniques can be used to reduce the offset of the opamp. These include autozeroing (AZ), which is a sampling technique, and correlated double sampling (CDS), which is a particular case of AZ and chopper stabilization (CHS) which is a modulation technique and can be used in continuous time system.