I agree with you that Champions League will be more competitive next season. The Leverkusen team is very strong despite not having many star players. On the other hand, Manchester City will try to strengthen their squad next season. Reigning champions Real Madrid have already managed to strengthen their squad by adding Mbappe to the squad.
Just by looking out the clubs we have already gotten an insight of how next season champions League will look like and the clubs that has a very higher chance of winning and also in the case of Liverpool I would say that they should just focus on the premier League for now because with what they did on this finished season I don't think they will survive on the champions League and also they are still going to go through a little declining in performance as there coach Klopp will no longer be with them next season, so getting use to the new coach will certainly take some time and also Arsenal on the other hand should also focus on the premier League more because that's were they have the higher chance on, however in terms of real Madrid they have already equipped themselves and they are ready for the champions League.
The upcoming champions league is becoming more interesting because of the increase in participants and several new clubs appearing in the champions league which gives a very interesting impression but big clubs such as Manchester City and Real Madrid will have to spend more energy because the match schedule will definitely be busier even though all clubs will improve performance but this will be a worry because a club like Leverkusen could be a surprise.
In the case of Liverpool, who has to focus on the Premier League, it seems that this is not necessary because Liverpool can focus on the group stage to stay in a safe position and get the opportunity to enter the UEL after the playoffs.
I understand how Liverpool is at the moment even without Klopp but this club deserves to try to get good results with its new coach.
For Arsenal, it is still the same as last season, whose ambition is to pursue the champions league title but will also lose the premier league title because getting the champions league and premier league titles will be a tough task and they must be truly consistent in maintaining the performance of Arsenal players.