An ext4 unix file system uses inodes to maintain the meta data of files like file names, attributes and tons of other data. Understand it that way this data structure builds the file system directory if you want.
Besides the file system journal the amount of inodes are what you see in this 119 GB already used space after format.
So, the number of inodes is the only “screw” you can use to change the preallocated space for the indoes. If you know that only large files will reside on such volume/disk, you can reduce the number of inodes by specifying
mkfs.ext4 -T largefile ... or even mkfs.ext4 -T largefile4 ... when you format the drive to ext4.
But be careful, the number of inodes can’t be changed anymore once it is set — otherwise you have to reformat the partition, again.
If you say 120 GB out of 8 TB is already used … this is around 1.5% of the total disk space.
Jfyi: I explained another user some days ago how to format a hdd to ext4 using OSMC, see Vero 4K+ and recording in TVHeadEnd - #10 by JimKnopf