Not only a striker but I think Arsenal needs a star player or an experienced player who can lift the team's mentality to be able to perform optimally, Arsenal's problem in the last 2 seasons is not only with the players but also things outside of that that cannot be controlled so that Arsenal always struggles at the end of the competition as if they cannot play as usual when under pressure.
Building a mentality is far more difficult because even though the team has sufficient quality players, efforts to win the title cannot be realized. This needs to be improved by Arsenal because indeed this team does not have a champion mentality, even though we see they are always able to dominate in three consecutive seasons that eventually fail to compete with Man City and Liverpool at the end of the season.
Striker is no less important but is much better when Arsenal can work together collectively and build a mentality to be better prepared to face pressure until the end of the season. If this can be formed then I am sure Arsenal will definitely reach the desired target in the next season.