you can do this through the recovery (in the menu) - see this screenshot: [HOWTO] use e-Recovery to wipe & format data before sideloading/install eOS (not the text)
How to enter the recovery mode depends on the device - you go into fastboot mode (early boot) and select via vol +/- the “recovery entry” - then the menu in the above screenshot appears.
The manufacturer publishes info on the keys that needed to be pressed: mostly either power + vol-minus or power + vol-plus. It’s similar across models of one manufacturer.