I want to add an icon when I will share my website page. May I get some help? I am using Magento 2.3.0
This depends on how you are sharing your page. Different social media services have different ways of relating to your page.
For instance, if you are sharing on Twitter then it is a 'Twitter Card' that you need. Many tutorials and third party extensions exist to add a Twitter Card.
You will need to be more specific to get the answer you seek.