All your online environments are backed up. 

System backups occur continuously by the underlying technology used by the Business Central service: Azure SQL Database. Databases are protected by automatic backups that are retained for 30 days. As an administrator, you cannot access or manage these backups because they are managed automatically by Microsoft. 

Note:  2020 Wave 2 update (Fall) there is a planned feature to provide control with regards to restoring at a point in time.  

FeatureEnabled forPlanned General availability
Restoring environments to a point in time in the pastAdmins, makers, or analysts, automaticallyOct 2020

For more information, we recommend reviewing the documentation about the Azure SQL Database automatic backups at FAQ for Dynamics 365 Business Central.