$ sudo diskutil apfs resizeContainer disk0s2 250g hfsx REPO 0b
..
Shrinking APFS Physical Store disk0s2 from 499,963,170,816 to 249,999,998,976 bytes
Shrinking APFS data structures
[ \ 0%..10%..20%..30%..40%............................... ] 47% 0:00:02
..
..
Initialized /dev/rdisk0s3 as a 233 GB case-sensitive HFS Plus volume
Mounting disk
1 new disk created or changed due to APFS operation
Disk from APFS operation: disk0s3
Finished APFS operation
uki 192.168.1.7 13:16 ~ $ diskutil list
/dev/disk0 (internal):
#: TYPE NAME SIZE IDENTIFIER
0: GUID_partition_scheme 500.3 GB disk0
1: EFI EFI 314.6 MB disk0s1
2: Apple_APFS Container disk1 250.0 GB disk0s2
3: Apple_HFS REPO 249.8 GB disk0s3
/dev/disk1 (synthesized):
#: TYPE NAME SIZE IDENTIFIER
0: APFS Container Scheme - +250.0 GB disk1
Physical Store disk0s2
1: APFS Volume SYSTEM 220.6 GB disk1s1
2: APFS Volume Preboot 22.3 MB disk1s2
3: APFS Volume Recovery 509.8 MB disk1s3
4: APFS Volume VM 1.1 GB disk1s4
REFERENCE:
http://www.peachpit.com/articles/article.aspx?p=1403238
https://www.macobserver.com/tips/deep-dive/resize-your-apfs-container/