As far as I have seen the spellcheck is not an option in WordPad which is a 'lite' version of Word but also pretty much a hold-over from Windows 3.x Write of the '90s, doesn't have many features. The Write.exe file still exists in Win11. WinKey + R, type write and press Enter. If not wanting to purchase a word processor program consider a free version such as OpenOffice, LibreOffice, etc., search on the Internet.