You are right, if Arsenal can get at least a draw in their first meeting then their chances become bigger, because in the second meeting they will play the match with home status, of course it is a very good opportunity for them.
But Porto is not a club that can be conquered easily, their presence in this round shows that they can indeed compete. In the group stage they also did not disappoint because they could collect 12 points from the 6 matches played, actually it was the same points that Barcelona had, but they lost in goal productivity so that only put them in 2nd place.
Arsenal are also in an unhappy state for sure, as they failed to win in their last match in the domestic league and kept them in 2nd place.
That's why, because Porto is not an easy team to beat, Arteta will prepare his squad to play the match with very high performance. moreover, this match will be held at the Estadio do Dragao, the home of Porto. if they are able to steal full points at the Estadio do Dragao, Porto's headquarters, the Gunners players will be happy to do their job very well. so, I'm quite sure that Arteta is not aiming for a draw in the first leg. theoretically, Arsenal will continue to use an offensive playing pattern. thus, it is certain that this match will be quite fierce. the problem is, the Gunners' young squad will be tested in this match. will Arsenal be able to overcome the obstacles when they visit Porto's headquarters, or will Arsenal experience the same thing as when competing at Lens' headquarters.
On the other hand, as the home team, Porto will not let Arsenal steal full points at home, that's why Sergio Conceicao will prepare his team's squad to fight with good performance when they face Arsenal in the last 16 of the Champions League. the opportunity to play in front of their own supporters in the first leg, Conceicao's squad will do their job by doing their job very well. but if we refer to what the betting bookies are providing for the time being, Arsenal is superior to the home team. however, these odds are only temporary. ahead of the match, it's likely that will change. unless Arsenal experiences problems or is otherwise in a positive trend.
Talking about Arsenal in the Domestic League competition, I think we still have lots of opportunities to remain competitive. after all, there are still a lot of games remaining until the end of the season. well, let's just wait before the Porto vs Arsenal match.