How to use custom excerpt

Depending on my post type, I’m using different custom fields for the excerpt. In the code below $thecontent is what’s showing for the excerpt in my search results template. I’m using this in tandem with search filter pro.

So the below code is for a search filter pro search. But I would like to use relevansi’s custom generated excerpt when there is a search string present… in the context of search filter pro, that’s the _sf_s query string.

How can I use Relevanssi’s custom excerpt in this case? I’ve looked at this page: https://www.relevanssi.com/user-manual/filter-hooks/relevanssi_excerpt_part/ … but it’s not clear how to use it in this context.

			$thecontent = get_post_meta($postid,'intro_text', true);
			
			if(empty($thecontent)) {
				$thecontent = get_the_excerpt($postid); 		

				$cust_excerpt = trim(get_post_meta($postid,'cust_excerpt', true));
				
				if(!empty($cust_excerpt)) {
					$thecontent = $cust_excerpt;
				}
			}

			if($posttype == 'people' && empty($thecontent)) {
				$thecontent = get_post_meta($postid,'automated_bio', true);
					$thecontent = strip_tags($thecontent);
					$thecontent = trim($thecontent);
			}
			
			if($posttype == 'calendar_event') {	
				
				$location = get_post_meta($postid,'event_location', true);
				$address = explode( ',' , $location['address']);
				
				$theaddress="";
				
				if(!empty($address)) {
					$theaddress .= $address[0].'<br/>'; //place name
					$theaddress .= $address[1].'<br/>'; // street address
					$theaddress .= $address[2].','.$address[3]; // city, state zip_close()
					$theaddresslink = 'https://www.google.com/maps?saddr=My+Location&daddr=" . $location["lat'] . ',' . $location['lng'];		
				} else {
					$theaddress .= get_post_meta($postid,'event_address', true);
					$theaddresslink = strip_tags($theaddress);
				}
				$thecontent="<a href="" . $theaddresslink . '" class="lib-card--address icon-map-marker">' . $theaddress . '</a>';
				
			} elseif( !empty($thecontent) ) {
				$thecontent = apply_filters( 'the_content', $thecontent );
				$thecontent = preg_replace("/<img[^>]+\>/i", "", $thecontent);

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