Maybe you are right that it will be difficult for Sevilla to stop Arsenal in the third match considering that they currently have momentum because they managed to win against their tough competitor in the English Premier League, but isn't that also the case when they face Lens? because Arsenal is the strongest team in the group but the result is quite surprising, so it is not impossible that Arsenal will get bad results against Sevilla later.
Sevilla, who saw an opportunity to beat Arsenal because seeing how Lens was able to do it, would not waste the opportunity because this was a home game for them, even though they were very bad in La Liga but there were different things shown by Sevilla when it was a competition in Europe, so I don't pretty sure Arsenal will win against Sevilla later.
Now it makes sense to say that previous matches and consistent performance in the Domestic League cannot be completely used as a benchmark, because playing in the UCL is very different. Of course everyone was shocked by Arsenal defeat to Lens, and it is evident that surprises happen more often in the UCL. Even though on paper Arsenal has a better chance than Sevilla, that doesn't mean the opposite can't happen, but if you look at the statistics, Arsenal should be superior.
Even though I'm not really sure Arsenal can get 3 points this time at come to Sevilla, I don't think they will lose that match. Sevilla has an advantage because they act as hosts, then they have to create their own luck while hoping that Arsenal doesn't play well so they can take advantage of it, because whether they admit it or not, Arsenal is still better than Sevilla.