3 Volts boost mode SPI

I am interested in using the DA14586 with a SPI peripheral at 3 Volts. The datasheet only barely mentions that you need to use boost mode to pull the GPIOs to the 3V rail - but it sounds like only a pullup resistor. There are no operating parameters shown for 3V operation and no examples of boost mode I can find on the reference designs. I found the definitions of GPIO_ConfigurePinPower() and GPIO_POWER_RAIL_3V in the SDK but, again, its not clear that the GPIOs can operate at 3 Volts. I need 3V push-pull for SPI.