The first match will be very difficult to predict, but the Manchester United vs. Arsenal match will be the same. This won't be easy for either team. Although Arsenal currently appears to be stronger, Manchester United remains a top Premier League team and must be reckoned with. This is a prestigious match for both teams.
Manchester United will be playing at home, and in their first few matches of the season, they have struggled to lose, so I predict the same, especially since Manchester United, playing at home, will certainly have much higher motivation.
Yes, this match is very difficult to predict. Arsenal is far ahead in terms of team strength. Since Manchester United will be playing at home and have signed some new players in the team, it would be very foolish to ignore Manchester United. Arsenal also knows that and they will try to take the first win of the season seriously in the first match of the season. Manchester United's big strength in the match will be the support of the audience, they will definitely try to taste the first win of the season with that strength by creating a great competition against Arsenal. I will not make any predictions now, I will wait for a great fight.