@mucr The network and sensors permissions don't exist on regular Android. They have been added by GrapheneOS. As such, apps don't know how to request them. Leaving them on by default is done to maintain compatibility. The reason other permissions are denied by default is because they're standard Android permissions and so developers know about them and ask for them when their app needs it.
However, there have been some recent updates that give you further control when it comes to these two permissions. The changes are as follows:
When you install a new app, you will see a checkbox for the network permission before actually installing the app. You can uncheck it to disable the permission.
There is now a setting to deny the sensor permission to new apps that you install by default.
You can find this setting at - Settings > Privacy > Allow Sensors permission to apps by default
If you disable the toggle mentioned above, apps you install won't have the sensors permission. If the app actually needs that permission (an example of this would be a compass app, for example), you will get a notification telling you that the app is trying to use them, and you will be asked to grant it that permission.
These features are demonstrated in this video as well: