Answer
No — Output Channels can't produce a genuine native .xlsx binary file; the closest available option remains fundamentally a CSV-style delimited text format. Using the 'other type'/custom-extension option and manually specifying an .xlsx extension is possible, but the underlying file content still remains comma-separated (or similarly delimited) text rather than becoming real Excel binary format. That said, a CSV-formatted file saved with an .xlsx-style extension can generally still be opened directly in Microsoft Excel without issue, even though it isn't genuinely native .xlsx underneath.