The teams from the premier league got enough money usually to hire good players and Liverpool is just one of them they got all they need with a coach like Klopp this won't be hard for them to play against the teams in the Europa League, but still can't be sure about Liverpool until we see some game from them in this season.
Whether or not Liverpool will be difficult in the Europa League is still uncertain as long as the season hasn't started because everyone still needs to see how Liverpool will perform from the start of next season. Even though Liverpool will definitely try harder next season, both in the Europa League and in their own domestic league because Liverpool also wants to prove that they still have the strength to fight and get a better place.