Why doesn't Samsung provide with a in-built applocker which can easily accessible from phone settings and can be used by face recognition or fingerprint other than using third party apps??
Use Samsung "S Secure" and "Secure Folder" If not preinstalled on your device then find out from Galaxy store.
S Secure: Keep selected apps and its data private by locking or masking them. Locking and masking can be done via a pattern, PIN, password, or your fingerprints. Apps will be locked once it closed or the device screen turns off.
Secure Folder: Secure Folder is where you can keep those photos, video, files, apps, and data you want to keep private. It's an encrypted space leveraging the defense-grade Samsung Knox security platform, protecting your important information from malicious attacks.
