Well having a dedicated /home
partition is the very minimum and pretty much default.
If you are interested in having a backup/restore solution for your system you are looking for BTRFS
which uses sub volumes instead of primary partitions and is compatible with snapshot tools, those tools being Timeshift and Snapper.
I do think Snapper is the superior solution however it's also more complex to set up and requires significantly more prep work. Imo totally worth it.
I currently use it on my main machine Debian with BTRFS and Snapper and couldn't be happier.
It's fine. "Only 27GB" is hardly too small for the system, even a bloated system wouldn't take that much space.
But if you must have a larger partition I think a reinstall would be easier, resize the partition is possible but because of the encryption not a straight forward thing. I wouldn't bother really.