First off, you will need some way to flash the SD card so download the appropriate version of Balena Etcher for your OS. Yes. There are a lot of other ways to copy images to an SD Card but Balena Etcher is probably the easiest and safest way to do it. It also works consistently for multiple OS's.

balenaEtcher - Flash OS images to SD cards & USB drives

The Easy Way

cl_reachy202012271141.iso.zip

The Hard Way

Flash SD card

https://www.raspberrypi.org/software/operating-systems/

Set up remote access