Check the cluster size of an exFAT drive on Windows

You can use wmic

C:\>wmic volume get driveletter,blocksize
BlockSize  DriveLetter
4096       D:
4096       C:

On powershell you'll have various solutions like below

PS C:\> (Get-Volume C).AllocationUnitSize
4096
PS C:\> (Get-WmiObject win32_volume | where { $_.driveletter -eq 'C:' }).BlockSize
4096

Alternatively you can also run fsutil fsinfo ntfsinfo drive: as admin to get more detailed information, or use fsutil fsinfo ntfsinfo <drive> | findstr /c:"Bytes Per Cluster" to get just the cluster size

Right-click the drive and click "format", and the pop-up window will show the current cluster size under "allocation unit size". Be careful that you don't actually format the disk though!