I once wanted to create a 100GB file to transfer it across a 10GB link to time the speed.
Below is the script that I ran in CMD to achieve this.
fsutil file createnew c:\users\ben\desktop\1gb.test 1073741824
I have added some file sizes below for referece
1 MB = 1048576 bytes
100 MB = 104857600 bytes
1 GB = 1073741824 bytes
10 GB = 10737418240 bytes
100 GB =107374182400 bytes
1 TB = 1099511627776 bytes
10 TB =10995116277760 bytes