Title. You can probably use any command that targets entities, but here's how I found out:
Spawn an entity, say a cat.
/effect give @p[type=cat] glowing
You'll notice that type doesn't pop up as an argument suggestion.
Finish typing the command, and press enter.
The command fails.
You have used the player selector instead of the entity selector. This is the correct command:
/effect give @e[type=cat] glowing