My USB drive lost most of its usable space.

[asterose]

Does anybody know the command Diskpart?  I got a 125 GB flash drive, ran WinToUSB_free.exe which writes Windows 10 to a bootable flash drive.  When it finished installing to the flash drive, I did a "dir" and was shocked to find it now only had 35 GB.  I did a long format (OS=exFAT) erasing drive contents, and when I did another "dir", there was still only 35 GB.

This is a replica of the input and output:

DISKPART> list vol

  Volume ###  Ltr  Label        Fs     Type        Size     Status     Info
  ----------  ---  -----------  -----  ----------  -------  ---------  --------
  Volume 0     C   Windows      NTFS   Partition     28 GB  Healthy    Boot
  Volume 1         Recovery     NTFS   Partition    700 MB  Healthy
  Volume 2         SYSTEM       FAT32  Partition    100 MB  Healthy    System
  Volume 3     D   ESD-USB      FAT32  Removable     32 GB  Healthy
 
DISKPART> list disk

  Disk ###  Status         Size     Free     Dyn  Gpt
  --------  -------------  -------  -------  ---  ---
  Disk 0    Online           28 GB      0 B        *
  Disk 1    Online          125 GB    92 GB
 
 DISKPART> select vol 3
 
 Volume 3 is the selected volume.

DISKPART> extend disk=1 size=92

Virtual Disk Service error:
The volume cannot be extended because the file system does not support it.

DISKPART>

Is there anything I can do to get back the rest of my drive space?

[Geek-9pm]

Did You Google?
A number or warnings have been given about using a  flash drive as if it were the same as a standard Hard Dive. In shot, they warn you not to assume they are .
Read this:
https://answers.microsoft.com/en-us/insider/forum/all/flash-drive-size-windows-10-recovery-drive/4c43feeb-c71b-414e-8af0-06e18b28fca7
My advice is just buy a plain 32 GB flash drive as an emergency boot for Windows 10 recovery. For backups, you want a a regular large size  HDD.