First look for OSS notes related to "Excel Spreadsheet export" on your system and your version of Excel. Not every tool is at same level, some are stuck in the good old (xls) 65,536 rows by 256 columns when last have exceeded those limits like (xlsx) 1,048,576 rows by 16,384 columns - Start with Note 1517329 - ALV Spreadsheet Export: Format Overview
Most standard tools (outside OLE2) that override currently the limit don't actually create Excel up-to-date files, but flat or xml compatible files that Excel will convert correctly. Actual conversion start with (AFAIK) class cl_xlsx_document, exception if of course scn abap2xlsx
Regards,
Raymond