Yes, you can change the system voltage (VSYS) and also disable the output on the SYS VOUT Control Register (0x06). The output can be programmable from 1.1V up to 3.3V.
Yes, you can also change the LDO/LS voltage and also disable the output on the Load Switch and LDO Control Register (0x07). The output can be programable from 800mV to 3.3V as a low dropout voltage regulator (LDO) or configure as a Load Switch (LS). Note the LS/LDO output needs to be disabled first before setting a new LDO value or before switching between LDO and LS.
