The official charger that Apple provides for MacBook Air M1 is 20v 1.5a or 15v 2a or 9v 3A or 5v 3A i.e. 30 watt.
It is always fine to use a higher wattage (i.e. 45 or 60 watt) power adapter on a Mac that shipped with a lower wattage (i.e. 30 watt) power adapter as long as the adapter’s connector fits.