Sure. Here are the steps. You will need two storage devices - one for installation (about 15Gb) and one for backup (your system size).
- Make a backup of your system with time machine on your backup storage device.
- Download Sonoma 14.3.1. Open a terminal and type there:
softwareupdate --fetch-full-installer --full-installer-version 14.3.1
3. Make an installation disk. Insert your storage device for installation with YourDriveName (replace it in the command) and type in the terminal window:
sudo /Applications/Install\ macOS\ Sonoma.app/Contents/Resources/createinstallmedia --volume /Volumes/YourDriveName\ macOS --nointeraction
4 Erase HD. Reboot your mac and hold power button to get into options menu. Go to Disk Utility and erase Macintosh HD. Make sure you have the backup already.
5 Install OS from the drive you made before. Insert you installation drive, reboot and select "Install MacOS Sonoma". Attention! Skip the update! Before starting the installation connect to WiFi.
6 Restore the system from time machine after installation complete.
Important. If there will be some troubles with apps like Steam or any games, install Rosetta and all will be fine.
/usr/sbin/softwareupdate --install-rosetta --agree-to-license
