AirTag Battery
I plan to use my AirTags on my luggage. Is there a way to turn off the AirTag when I am not traveling to preserve the battery?
The only way to power it off, would be to remove the battery ... which, of course, would defeat its purpose. The AirTag battery should last a considerable amount of time and you may find this technique not to your advantage.
Ref: How to replace the battery in your AirTag - Apple Support