Hello
Thank you for the clarification. If you need to configure gains higher than 1 V/V, this cannot be done using the 16‑bit CH_GAIN field, since its maximum value is 0.8 V/V.
Instead, you must use the 24‑bit calibrated coefficient registers, specifically:
GAIN_COEF0..15 — addresses 0x80h–0x8Fh

Please see section 7.3.6 Gain and offset calibration and Table 30. 24-bit channel-based coefficient and data registers
These registers allow you to apply any effective gain greater than 1 V/V, since they function as 24‑bit multiplicative calibration coefficients.
Hope this helps!