How crash recovery process works in SQL Server?
The Comparison of RECOVERY and NORECOVERY section of the RESTORE Statements doc should help you with that question:

Rollback is controlled by the RESTORE statement through the [ RECOVERY
| NORECOVERY ] options:

NORECOVERY specifies that rollback doesn't occur. This allows    rollforward to continue with the next statement in the sequence.
In this case, the restore sequence can restore other backups and roll    them forward.

RECOVERY (the default) indicates that rollback should be performed    after rollforward is completed for the current backup.
Recovering the database requires that the entire set of data being    restored (the rollforward set) is consistent with the
database. If    the rollforward set has not been rolled forward far
enough to be    consistent with the database and RECOVERY is
specified, the Database    Engine issues an error.