IIR Filter implemented in MKRzero and simple rate


I am trying to implement infinite impulse response (IIR) in MKR zero board. I saw in documentation that rate of sampling is 350ksps from chip datasheet. While, the resolution of MKR ZERO board ADC is 12bit which can be change by analogReadResolution(bits). But, I didn’t see neither in the datasheet or the arduino site a way to modify or know the simple rate of the ADC.

Is there a way to modify a register in MKR0 (ATSAMD21G18) to adjust the simple rate ?

Is there a good example of IIR filter for MKR0 Arduino ?