Hi @Priyanka_Singh,
The encryption at rest in Atlas encrypt the database files on disk and backups, so if someone would get there hands on this data they will not be able to restore it.
However, the data is decrypted when authenticated and whitelisted clients like compass access the data. This decryption/encryption is by design and for the whole instance.
The recommended features to encrypt client visible data is FLE :
By the way any connection to atlas is TLS encrypted by default.