Even then, any weak team can play well in home matches. A few days ago we saw Lazio win against a strong team like Bayern Munich. So Arsenal players must play very carefully. If Arsenal players play carefully then it will not be difficult for them to win against Porto.
On paper, even though Arsenal act as the visiting team, they have a big chance of winning the match, Arteta has a more even squad depth this season. Several players who have experience in winning the UCL trophy are a priority for Arteta to include in the starting XI. Arteta must be able to pump up his players' motivation and improve his players mentality, because the Champions League atmosphere is very different from the EPL.
On the other hand, Arteta and his fleet also have to learn from the experience of the previous group phase, where they lost surprisingly to Lens, even though we know they were on fire at that time. If they can manage their mentality well, it will make it easier for them to win over Porto.