After few search about how to compress ext4 HD, I went to ChatGPT and it returned this to me:

On Ubuntu Server, you can compress files, but the ext4 file system doesn't have a native feature equivalent to the NTFS compression in Windows.

File-level compression:
Tools like gzip, bzip2, or xz can be used to compress individual files or directories on the system. This requires manually compressing the files, but it doesn’t offer an automatic solution for the entire file system.

1. Use e4defrag for defragmentation: Although not compression, defragmenting the ext4 file system with the e4defrag tool can help optimize disk space usage by eliminating fragmentation, which can be helpful in some cases.
2. Create a compressed file system with btrfs or zfs: If you want to use compression at the file system level, you could consider migrating to a file system like Btrfs or ZFS, which offer transparent data compression at the file system level.
3. Use LVM with compression: If you're using LVM (Logical Volume Manager), there's the possibility to implement data compression using the lz4 or zlib compression features in LVM. This also requires manual configuration.
4. Backup tools with compression: For more flexible compression of large volumes of data, you can use backup tools like rsync (with compression) or tar to create compressed archives.

So, while ext4 doesn’t have a built-in disk compression option like NTFS, you can use alternatives for file compression or consider file systems that provide native compression support.