Even if you leave your phone for repair now, the technician will not be able to access everything stored on your Samsung phone.

Samsung has already started rolling out the “Maintenance Mode” feature globally. The feature promises to protect the data and content on the device when you need to grant it to others
The feature is now being implemented worldwide as part of OneUI 5 features. This feature is called “Maintenance Mode” and it proposes a simple way to hand over our mobile phone to the technician without worrying about our data:
“Maintenance Mode is a way to create a separate user account when handing over your device for repairs so that they can carry out core functions without being able to access your personal information.”
In other words, we will have a dedicated account only so that the technician can access the functions of the mobile phone, or download applications if they need to carry out tests, which will work independently of our main account.
So all the data and content that we have stored on the mobile phone will be hidden from the technician. Once the technical service is done with the repair, you can exit “Maintenance Mode”.
Once this action is taken, all apps or data that were downloaded during the repair and saved while this feature was activated will be automatically deleted from the device. And of course, the user will be able to use the mobile normally.
To activate this feature, we just need to go to Settings & gt; & gt; Device Maintenance & gt; & gt; Maintenance Mode . The feature will work as long as the device is in conditions that ensure its operation.
The Samsung team mentions that this feature is already being rolled out on the Galaxy S22, S22 Plus, and S22 Ultra, but they plan to bring it to other Galaxy phones running Android 13 with OneUI 5 in the future. It will be released during the remaining period of 2022 and throughout 2023.