There are many standard reports in GA4 that are readily available.  If your analysis goes beyond that then head over to "Explorations" which was previously called "Analysis Hub".  (Given that these are still early days for GA4 this may change again.)  

Pugpig Custom Dimensions

To get the most of these reports it is important that our custom dimension have been added to your account.  

To check if they have been added head over to Configure / Custom Dimensions and will begin with the letters "KG" example, KGPageName, KGEditionName etc.  If they are not there follow these instructions to add them.

Explore Reports

Creating reports in this section will allow you to:

• quickly perform ad hoc queries
• drill down into the data
• easily switch between different techniques
• combine various dimensions and metrics
• ability to add filters and segments
• export data into GA segments or audiences
• export data into other tools

FAQ's

Why can't I edit a report that is available in explore?

If you have been given access to a report in Explore that has been created by somebody else GA4 does not allow you to edit it.  To edit it, you need to duplicate the report and then edit the duplicate.