Search for your specific model, it may or may not be this link, but for a Zenbook 14 this came up after searching “ASUS Zenbook 14 support”.
https://www.asus.com/supportonly/ux3402za/helpdesk_bios/
You’ll need to format a flash drive and save the BIOS update to it, then boot into BIOS and run the update. For many laptops, instead of saving a BIOS update to the drive you may need to run a setup tool (usually a .exe, so may need compatibility tool) and boot to the USB.
As for frequency, just periodically check the notes for the BIOS releases and determine whether to update based on the features or patches in it. Not necessary to update for everyone one, and many security updates will be more for servers than general purpose personal computers, but that’s up to your own risk analysis.
This is the sort of stuff I was excited about AI for in the 2010s when development started showing results. Before tech(bro) companies ruined the term.