Plasma Vault is an open-source encryption solution for KDE Neon with which you can create encrypted folders to contain private files of any format.
How is the encryption that Plasma Vault provides different from that of the default encryption that Ubuntu (for example,) lets you perform on your Home folder? Ivan ??uki??, the developer explains:
[An encrypted home folder does] not cover the possibility that someone might access your system while it is running. Plasma Vaults fill this void by making the attack surface smaller – instead of having all data unlocked at once, you can do it piece by piece – it is more granular.