What's the safest way to update my 2020 MacBook Air to Ventura?

1- Make sure the current version of Monterey is fully Up To Date which would be version 12.6.1 Monterey.

2 - Make sure there is at least 15% - 20% of the Total Drive Capacity of the computer is Empty Space. This will allow the 12.16 GB Full Version of Ventura to download, expand and only then commence the Installation Process.

3 - Where possible connect via an Ethernet Cable to Router for better speed and reliable connections

4 - Remove any AntiVirus Software Before attempting the upGrade

5 Have a Rescue Plan comprising 2 Methods ( Time Machine Backup and a Clone ) each to separate external Drives

Safe mode shouldn't be necessary. The only thing that seems necessary is to make sure you have a backup before updating.

You make sure all of the software you depend upon will work with Ventura, ensure your backup is current, then you upgrade.

What are you expecting to be somehow unsafe?