View or Update Salesforce Object Permissions via the Developer Console

1. Open the Developer Console.

Salesforce Classic:
Click Your Name | Select Developer Console.

Lightning Experience:
Click the quick access menu (Setup gear icon) | Select Developer Console.

2. Choose the Query Editor tab.
3. Input the query.

Example query:
SELECT Id, ParentId, SobjectType, PermissionsViewAllRecords, PermissionsModifyAllRecords FROM ObjectPermissions WHERE SobjectType = 'Create_Contact__e' and ParentId = '0PS2E000002Iw7a'

4. Click the Execute button. 
5. Double click on the row of the column to update. Make changes.
6. Click Save Rows button. 

NOTE:
SobjectType value refers to the API name of the target Object or Platform Event.
ParentId value refers to the target Permission Set Id. 

To get the object Id:
Standard Objects - Refer to Object Reference for Salesforce and Force.com . Select the object  to get API name.
Custom Objects - Review the section Naming Conventions for Custom Objects of the Developer Documentation.
Platform Event - Similar to custom objects, this can accessed on the Platform Event setup page.


There is an existing Known Issue, Unable to assign permission set to users due to View All being enabled on Platform events, which uses these steps as a workaround.