In order to customize your Safari tool bar, you can alter your buttons. All you have to do is click on "view" and "customize tool bar". Select a button that you like from the 2 rows in display. Then, click on the button you would like to add to your tool bar and drag it to your tool bar. You can use buttons as shortcuts to go back and forward, with the back and forth arrows and to take you to your favorite sites, with "top sites". There is not refresh button, because it isn't necessary. It's in your browser. You'll just need to decide how many and which ones you want to use regularly.
Have an iPhone? Check out all 200+ new features coming in iOS 13.