I'm sorry, I did not quite understand this part. Is something preventing you from formatting the card in Chromebook?
Ext4 would be my choice, but if you need to access the card in Windows as well, choose FAT32. It works everywhere, even macOS can read it. The only downside is that it's not a journaled filesystem, so you need to remember to use the "safe removal" option of the OS to unmount the card before removing it - if such option is available.
If you are planning on doing it in Linux, Gparted is a good, reliable tool. If there are partitions on the disk, you can remove them in Gparted, then create one partition of 128GB and format that to FAT32.
Some guidance here:
How to Format a Hard Drive Using Ubuntu (with Pictures) - wikiHow