The USB Im using is 16gb and the Windows 11 ISO is 6gb so I shouldnt have a problem but its saying I dont have enough space. Apparently it has something to do with formatting or something?? (i have no idea pls help)
The other comment is correct.
To add some context, if the USB has been formatted before (so that you can open it like a normal drive and put files in there), that means there is already a partition (a 16GB one). Some partitions can also use older file systems have a small maximum file size, this might be the issue if you just want to store the file on the USB.
If you use the Disk Management tool in Windows, you can delete the partition.
Then either you can create a partition with a different file system that supports large files, or create a bootable Windows ISO using Rufus, and likely you will still have room on the drive to create a second partition afterwards out of the unused space if you want.