Power adapter

Yes.

Excerpted from Find the right power adapter and cable for your Mac notebook:

"If your Mac uses USB-C to charge, you can charge your Mac notebook with any USB-C power adapter or display."

I have used the 61 Watt Apple supply without any problems. Regardless of the power rating of the supply, the MacBook Air will use only what it needs. It may improve the speed of charge while using the MacBook Air with high intensity CPU/GPU apps, but not really enough to be noticeable.