elastic-press-custom-weighting.php

function SetSearchArgs( $formattedArgs, $args = [] ) {

	if( isset( $args[ 'post_type' ] ) && ( count( $args[ 'post_type' ] ) > 1 || gettype( $args[ 'post_type' ] ) === 'string' ) ) {

		if( gettype( $args[ 'post_type' ] ) === 'array' ) {

			$existing_query = $formattedArgs[ 'query' ];
			unset( $formattedArgs[ 'query' ] );
			$formattedArgs[ 'query' ][ 'function_score' ][ 'query' ] = $existing_query;

			foreach( $args[ 'post_type' ] as $postType ) {

				$formattedArgs[ 'query' ][ 'function_score' ][ 'functions' ][] = [

					'filter' => [
						'multi_match' => [
							'query'  => $postType,
							'fields' => [
								"post_type.raw",
							],
						],
					],
					'weight' => (int) [ INT ],

				];

			}

		}

	}

	$formattedArgs[ 'query' ][ 'function_score' ][ 'score_mode' ] = 'sum';
	$formattedArgs[ 'query' ][ 'function_score' ][ 'boost_mode' ] = "multiply";

	return $formattedArgs;

}

add_filter( 'ep_formatted_args', 'SetSearchArgs', 300, 2 );