Is it possible to add extra share icons? If so, how?

See How can I add a custom share button? and How can I add a custom follow button? in the plugin’s FAQ.

You can use the Code Snippets plugin to add the suggested PHP code to your site instead of adding the code to your theme’s functions.php file.

Thank you sooooo much for the prompt reply. I really, really appreciated. You are super!

I added a custom button in this way
How can I add another custom button?

@katameslim Here’s an example of multiple custom follow buttons, and it’s the same syntax for share buttons.