How do I create a shadow around quote?

Now please help add shadow like effect around quotes.

Can you specify what do you mean by quotes? Can you link us to a post and point us to the quotes?

https://www.wplogout.com/create-custom-footer-in-generatepress/

Check the post above.

Scroll a few paragraphs, and see the "Recommended Reading."

I want to create that type of box.

This box is basically a paragraph block with alsoread in its additional CSS class(es).

And here's the CSS involved with it:

.alsoread {
    font-weight: 900;
    border: 1px solid #dcdee3;
    border-radius: 5px;
    box-shadow: 0 4px 15px rgb(0 0 0 / 10%);
    color: #16a085;
    padding: 15px;
    background: linear-gradient(to right,#eee,#eee);
    border-left: 3px solid #b11f24;
    font-size: 20px;
}

Also I would like to add "Read More" on archive page like this..

Check that same website:

https://www.wplogout.com/blogging/

That site is using this styling:

/* Read More Style */
a.read-more.button {
	font-size: 16px;
    background-color: rgba(255, 255, 255, 0);
    color: #115cfa;
    text-decoration: none;
    background-image: linear-gradient( transparent 2px, #2ed392 2px, #2ed392 4px, transparent 4px ), linear-gradient( transparent 2px, #d8dce9 2px, #d8dce9 4px, transparent 4px );
    background-size: 0% 6px, 100% 6px;
    background-position: 0 bottom, 0 bottom;
    transition: background-size 0.3s ease-in-out;
    background-repeat: no-repeat;
    padding: 10px;
	font-weight: bolder;
}

a.read-more.button:hover{
	color:#115cfa;
	background-size: 100% 6px;
	background-color: #115cfa00
}

The css you gave didn't work.

I'm using custom excerpt in all posts. So "Read More" isn't showing. Is there any way to still show that despite having custom excerpt?

You can try adding this PHP snippet for that:

add_filter( 'wp_trim_excerpt', 'tu_excerpt_metabox_more' );
function tu_excerpt_metabox_more( $excerpt ) {
	$output = $excerpt;
	
	if ( has_excerpt() ) {
		$output = sprintf( '%1$s <p class="read-more-container"><a class="read-more button" href="%2$s">Read more</a></p>',
			$excerpt,
			get_permalink()
		);
	}
	
	return $output;
}

I want to add an arrow after Read more link...

Like this:

Read More ->

add_filter( 'wp_trim_excerpt', 'tu_excerpt_metabox_more' );
function tu_excerpt_metabox_more( $excerpt ) {
	$output = $excerpt;
	
	if ( has_excerpt() ) {
		$output = sprintf( '%1$s <p class="read-more-container"><a class="read-more button" href="%2$s">Read More -></a></p>',
			$excerpt,
			get_permalink()
		);
	}
	
	return $output;
}

Try this.

Can you open a new topic if there are follow-up questions? So the topic doesn't get too convoluted as the follow-up questions are not related to the topic's initial question. Thanks! :)