The Arduino Nano 33 BLE has the ability to change its analog read resolution increasing the number of bits on the values that
analogRead() function returns. The default resolution value is 10-bits (returns values between 0-1023) and it can support up to 12-bit ADC (returns values between 0-4095).
To achieve this there is another function called
analogReadResolution() that sets the size (in bits) of the value returned by
See the analogReadResolution() page for more information on how to change the ADC resolution.