reset of MacBook Air m1

Follow the steps in this article:

What to do before you sell, give away, or trade in your Mac - Apple Support

and make sure you're brother has done all of the necessary thing he should have before giving to you, especially anything that is related to his AppleID because if not, there will be issues in the future.

To perform this action will require booting from a Bootable Installer. This will have to be performed from a Qualifying Computer to run the version of macOS to be made on the Bootable Installer. Example : Bootable Installer of Big Sur would have the done on a computer that Qualifies to run Big Sur.

Once that is done read on for preparing the Destination computer  >> Special Notation - works on Intel Based Apple Computers & May on Apple Silicon M1 CPU

Extra Special Notation regarding the Touch ID equipped Apple Computer. About Startup Security Utility and Must Enable from Recovery Mode the ability to boot from External Drive Before Attempting 

Understand - the next step will Erase everything on the Computer. There is no going back at all.

Shutdown computer and disconnect all external drive Except the newly created Bootable Installer. Restart and immediately hold the OPTION key until the Startup Manager appears and choose the USB Drive. It will present options >> Disk Utilities >> View >> View ALL attached Drives. Choose the Upper Most Drive ( not the volumes indented and list below ). The drive normally is called Apple Media or Apple SSD - that is the drive to Erase and format as APFS with the GUID Partition Map. Once that is done >> backup out of Disk Utilities and choose install macOS. Follow the prompts and it may automatically reboot several time. Upon a final reboot - Setup Assist will present with the newer version of macOS.

Hi bhim26,

That functionality hasn't reached Macs just yet, but it will in a couple of months. The next release of macOS (macOS Monterey) will include an easier way to erase your Mac, described below.

In the meanwhile, please see woodmeister50's reply for how to erase your Mac.

In macOS Monterey:

NOTE: This will only work if your Mac has the T2 Security Chip or uses an Apple silicon chip (such as M1).

1. Log in to an administrator account.
2. Open System Preferences.
3. At the top of the screen, select System Preferences -> Erase All Content And Settings.
4. Follow the onscreen instructions to erase your Mac.

The MBA M1 and doing Like iPhone Reset is more complicated and risky. What exact issue is being experience that would require a Reset. Details please.

Agree with @ woodmeister50.

That method is Much Better and easier to do.