Method: channels.searchPosts

Parameters:

Name	Type	Required
hashtag	string	Optional
offset_rate	int	Optional
offset_peer	Username, chat ID, Update, Message or InputPeer	Optional
offset_id	int	Optional
limit	int	Optional

Return type: messages.Messages

Can bots use this method: NO

MadelineProto Example (now async for huge speed and parallelism!):

if (!file_exists('madeline.php')) {
    copy('https://phar.madelineproto.xyz/madeline.php', 'madeline.php');
}
include 'madeline.php';

$MadelineProto = new \danog\MadelineProto\API('session.madeline');
$MadelineProto->start();

$messages_Messages = $MadelineProto->channels->searchPosts(hashtag: 'string', offset_rate: $int, offset_peer: $InputPeer, offset_id: $int, limit: $int, );