Safari update
How can I update safari to use Whatsapp application?
iPad Pro 11-inch Wi-Fi
Question marked as
Safari is updated along with iOS. To learn how to update iOS please read Update your iPhone or iPad - Apple Support.
If you are using the latest iOS version yet the "WhatsApp web" website is asserting the need to update it, then the website is defective and mistaken in that assertion. Only its developer can fix that: Contact a third-party vendor - Apple Support.