SQLite is "unsecure" out-of-the-box (as in: No User/PW-Authentication and/or encryption).
So if you share the db-file on a shared network-folder, anyone who has a client for SQLite (e.g. DB Browser for SQLite), is able to open it "directly" (and manipulate it), given that that user has access to that folder.
IIRC, SQLite has a authentication-system in place, but you would have to compile it yourself to include that option.
No idea about encryption. Never used it.
If a Database transitions from "single-user" to "multi-user", i'd really think about using a "real" db-server (e.g. MySQL, PG, FB), especially if you need parallel read/write-access