You may use the tool
split to split a file by sizes.
An example to split a large.tgz to at most 8GB smaller files is as follows.
split -b 8G large.tgz large.tgz.part-
The split files names are the prefix with appendix like 'aa', 'ab', 'ac' as follows.
$ ll -h
-rw-rw-r-- 1 user user 18G Jun 25 10:57 large.tgz
-rw-rw-r-- 1 user user 8.0G Jun 25 12:10 large.tgz.part-aa
-rw-rw-r-- 1 user user 8.0G Jun 25 12:15 large.tgz.part-ab
-rw-rw-r-- 1 user user 1.2G Jun 25 12:16 large.tgz.part-ac