So it has been confirmed, 2024 Land Cruiser require's Premium Fuel.

[Bronconomore]

Being in Southern California, where the gas prices are the most in the nation, premium 92 octane is frequently 20 cents or higher. Would my LC be knocking if I still use 89 octane regular. How much damage can be done if I use regular only?

Do you want to roll that dice and have your engine warranty possibly null and void? If the knocking causes an engine issue?
Not I. But to each their own.