What if the match ends in a draw and goes to penalties?
The game hasn't started yet and anything can happen as Madrid have a good plan to score 3 goals and defend until the end of the game. If Madrid manage to end up in the penalty shootout, I believe Madrid have a great chance.
but on google I see Real Madrid is favored in that match but of course if I will favor Arsenal's victory because I have a feeling Arsenal will win.

Favour Arsenal to win the match or favour Arsenal to qualify to the semi finals? Even if Madrid win the match by less than 3 goals, Arsenal will still qualify for the semi finals.
So, betting on Arsenal to win is high risk for me.
If Real Madrid is in their best condition and all the players are in their best performance then it is still possible for Real Madrid to score 3 goals against Arsenal. The problem is that Real Madrid in the last few matches have not been able to return to their best performance. Some of their players also haven't been able to show their best performance. But if the match ends in a penalty shootout, then Real Madrid will be very favored to become the winning team. Because we know this team's mentality when it comes to penalties is beyond doubt.
Today, every home team managed to win a match, namely Aston Villa managed to beat PSG in the second leg, although it was still PSG who qualified for the next stage, then Dortmund also managed to beat Barcelona in the second leg, although it was still Barcelona who managed to move forward, and it is possible that the same thing could happen in today's two matches. Except for the Inter Milan vs Bayern match, everything is still unclear because an aggregate advantage of 1 goal can change direction quickly.