Answer
As θ increases, $f_{s,max}$ decreases.
Work Step by Step
The equation that guides the thinking in this problem is:
$f_{s,max}$=Coefficient of Static Friction×FN
The coefficient of static friction is always the same, so only the normal force is taken into account. The normal force has a direct relationship with $f_{s,max}$, so as the normal force increases, $f_{s,max}$ increases. Increasing $\theta$, decreases the normal force, meaning that it also decreases $f_{s,max}$.
