How to Override Block in Magento 2
I am going to teach you how to override blocks in Magento 2, but before starting the tutorial, let’s understand what a block is ? PHP classes is used to create a link between templates and layout known as Blocks. Class is a se of methods that handles and control the Magento UI Blocks. Also it has the following features :
A block can have more blocks.
A block can be utilize in different pages and blocks.
You need to create a custom module to override block in Magento 2 and after that you will do the following things :
Create directories
Configure Module
Register Module
Override di.xml File
Override Contact Form
Override contact_index_index.xml
Override form.phtml
Run Commands
You can view the codes of the mentioned steps here at How to Override Block in Magento 2