Although I don’t have Office 2019 like you do, I guess you save it simply as Excel workbook. Your file will then have an extension name of “.xlsx”. All Excel files earlier than 2007 are saved with the “.xls” extension name.
By all means, you have to! Your use of the word “look” reminds me of the proverb: Look before you leap is an excellent maxim but don’t make the mistake of looking too long for you may never leap! Succinctly stated, look now, or never look!