improving battery life for macBook Air M1
Just use the Mac!  But you can help it with:

Make sure &quot;Optimized battery charging&quot; is on.  System Preferences &gt; Battery.
Avoid having power connected all the time, though this is mitigated by macOS and the setting optimise battery charging.
Avoid letting the battery go below 25%, but if needed sometimes don't worry.
If you are going to turn it off for many weeks, let it run down to 60% before turning it off.
Avoid high temperatures by keeping air flow around the MacBook - for example, don't rest it for long on soft bed covers.

Apple don't say, but battery is probably happiest between 40% and 80%.
Edit:
Apple are very reticent about precise advice regarding battery health. The most recent Apple battery support note has no advice on maximising battery health - only about battery life (time usable on battery power).  The only reference to battery health is the tick box for &quot;Optimized battery charging&quot;.
How to Prolong Lithium-based batteries is a relatively recent general discussion of strategies to assist battery health. In particular Figure 6 shows the effect on batteries due to to different use and charging strategies with maximum battery lifetime being from keeping the battery between 65% and 75% at all times.  Read this (and some of its links) with interest and to gain some understanding of battery performance - but not to hamper use of the new MacBook Air.