You cannot hope to get high-precision, low-noise results without a high-precision, low-noise design!
And, unsurprisingly, a high-precision, low-noise design is not a trivial exercise.

I have seen more posts than I have fingers where someone confused precision with resolution.

I specifically recall a sentence "my chip must be bad, the ADC jumps between readings of 1200 and 1233". Further in te therad it was revealed that he used a one or two layer board with no ground plane, no separate analog ground .... and the cause of the 'erratic' readings, he insisted was the chip that claimed 24 bits.

Erik