Convert XLSX to WK1

xlsx to wk1 conversion represents the export of modern Excel spreadsheets (.xlsx) to old .wk1 files from some earlier versions of Lotus 1-2-3, which is somewhat odd export to be honest. This is theoretically doable, but you would have to either find a software that can still save to WK1 format, or use some middle step conversion (for example to CSV) and use ancient version of Lotus 1-2-3. In any case, only data from the tables will be exported, it is unlikely that modern Excel formatting can be used in old spreadsheets.