Power BI Report Builder Export Formatting

Hi,cheid_4838 
I am glad to help you.

According to your description, you are experiencing incorrect formatting when exporting a paged report to excel using the report builder and you want to be able to preview the formatting before exporting it

If my understanding is correct, you can refer to my suggestions below:
1.First of all you need to know about some limitations regarding export to excel. This may be the cause of the problem with the alignment of the exported file as well as the expanding, collapsing and other functions.
like this:

Here is the official document about exporting to Excel format, I hope it will be helpful for you
url:
Export Power BI paginated report to Microsoft Excel (Power BI Report Builder) - Power BI | Microsoft Learn
Export Power BI paginated reports (Power BI Report Builder) - Power BI | Microsoft Learn

2.You can adjust the layout of the report according to the limitations of exporting to Excel and the things you need to pay attention to the layout in the document.

The official documentation on page layout and presentation in paged reports is shown below and we hope it can help you.
URL:
Page layout and rendering in Power BI paginated reports - Power BI | Microsoft Learn

I hope my suggestions give you good ideas, if you have any more questions, please clarify in a follow-up reply.

Best Regards,

Carson Jian,

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