As per the image, I would like to add extra style for the table block.
register_block_style function is what you’ll want.
The basic implementation is
register_block_style( 'core/table', array( 'name' => 'my-table-style', 'label' => 'My Table Style', ) );
When you select the style, it will add the
is-style-my-table-style class to the block, which you can style using your
style.css or other stylesheet.
There are two other implementations, where you can declare an inline style or a whole stylesheet for that specific style. You can find more details in the documentation: https://developer.wordpress.org/block-editor/developers/filters/block-filters/#register_block_style