Last year, we have discussed how to save the report as a PDF, Excel, Word, HTML, or XML file.
More details: Dynamics 365 Business Central: How to save the report as a PDF, Excel, Word, HTML, or XML file (Report.RunRequestPage Method and Report.SaveAs Method) | Dynamics 365 Lab (yzhums.com)
As you might know, Report.SaveAsPDF() function or Report.SaveAsExcel() function not supported in Business Central Cloud SaaS (Cloud). So I tried to save report in Stream objects then convert to file using BlobExport function.