What happens if Liverpool wins europa, which is direct UCL, but also they are in top four as we know, so they are going to UCL anyway. I am not entirely sure if that spot goes away, like they just get one, or does that mean fifth of Premier league goes to UCL? Not really well versed in that regards.
In any case, there is no guarantee that Liverpool would win europa, there is a possibility that they could lose along the way. Yes they are the better team, but check the past five years and quarter finals till finals, you will see many good teams end up losing to unexpected teams (mostly to sevilla lol) so you will realize that Liverpool may not end up winning at all. That means nothing will change with the situation.
If Liverpool succeeds in winning the Europa League then they will qualify for the Champions League playoffs. However, if Liverpool manages to finish in 1st to 3rd in the Premier League, they will automatically qualify for the Champions League group phase. Liverpool may appear to have a better performance than their rivals in the Europa League but I think becoming the European League champion is not that easy because AC Milan, Roma, and Bayer Leverkusen are opponents who could become obstacles for Liverpool. But first, they have to get rid of Atalanta, which is also not an easy opponent to beat.