Developers never know everything, they just know when something exists, and also know how to look it up.
For example, say you wanted to find out how to search for the cursor that changes to a hand when you hover over a button. You might type something like: (in the search bar)
“css property to add mouse cursor to button”
In stackoverflow.com you will find that you can just put button {cursor: pointer;} into your css code.
OR
“css how to center anchor elements” OR go more specificly to “mdn css text align”
In stackoverflow.com you will find that the answer is to add the text-align property (text-align: center;) to its parent style attribute
developer.mozilla.org is a good reference resource for developers. Mdn explains and gives examples to test, which is always a good thing.