Image from link

I’m sorry if this is replied earlier, but I haven’t found it. I’m grateful for the Recent Facebook Posts plugin, it’s great! I’m just wondering how the image from a link is grabbed and how I may change it.

The grabbed image is now 154 px wide, but the link image when viewed on Facebook is 377px wide. Is it possible to change the code so that I may grab the biggest version of the image?

This is the code I guess is relevant, (but I don’t know how to change):
class-public.php

elseif ( $p->type == 'link' ) {
				$post['link_image'] = ( isset( $p->picture ) ) ? $p->picture : '';
				$post['link_name'] = ( isset( $p->name ) ) ? $p->name : '';
				$post['link_caption'] = ( isset( $p->caption ) ) ? $p->caption : '';
				$post['link_description'] = ( isset( $p->description ) ) ? $p->description : '';
				$post['link_url'] = $p->link;

class-api.php

public function get_posts()
	{
		$result = $this->call("{$this->fb_id}/posts", array(
			'fields' => 'id,picture,type,from,message,status_type,object_id,picture,name,caption,description,link,created_time,comments.limit(1).summary(true),likes.limit(1).summary(true)',
			'access_token' => "{$this->app_id}|{$this->app_secret}"
		));

RFBP_API.php

public function get_posts()
	{
		$result = $this->call("{$this->fb_id}/posts", array(
			'fields' => 'id,picture,type,from,message,status_type,object_id,link,created_time,comments.limit(1).summary(true),likes.limit(1).summary(true)',
			'access_token' => "{$this->app_id}|{$this->app_secret}"
		));

RFBP.php

elseif($p->type == 'link' && !stristr($post['content'], $p->link)) {
				$post['content'] .= (empty($post['content'])) ? $p->link : "\n\n" . $p->link;
			}

https://www.ads-software.com/plugins/recent-facebook-posts/