Your Apple device didn’t come with a manual in the box, but they are available for free, and they are very nice.
Apple publishes manuals for all their hardware and software and makes them available in the Books App. The Books App is included on every Macintosh, iPad and iPhone.
There are very nice manuals for every model of Macintosh, iPhone and iPad, as well as Apple Watch, Home Pod and Apple TV.
There are users guides for iOS, Pages, Numbers, and Keynote.
Of course, there are many other books in the store about these subjects, by many different publishers, and most of them are not free.
Once you’ve opened the Books App, to find the free, Apple-published items, look for the Apple User Guides link on the right hand side of the Books App, under Quick Links. The guides are usually named either User Guide or Essentials, for example, iMac Essentials, or iPhone User Guide.
You will definitely learn something from these. Amaze your friends and family with your expertise — Read the Manual!