You’ll need to learn about two things here:
Extend the Collision Presets of any object to get an idea about the built-in collision channels (and read that page, it’s good).
A Power-Up should not have any blocking collision at all, but an overlap (and an overlap event handler to apply the power-up). Projectiles on the other hand often use the Projectile-Preset and apply damage on hit/overlap.
There is a power-up Content Example Project which uses a “base class” for Power-Ups and for each type it has an Child-Class which applies the specific effect. There is even an explanation of child-classes in the docs, using that power-up example: Child Blueprints