How to: Trigger Enemys / Items?

Hello!
I am quite new to Unity and programming at all. I already made some mini-games and wanted to try making something bigger now, a little RPG.
already in my planings i now found a problem i dont know how to handle: Some things in my game shall be triggered when the player is getting closer to them, like enemys that start chasing you when they "see" you, or dialoges being displayed when standing near to an NPC. But I do not know how to script this. I already thought of a way: creating a invisible sphere around the enemy/npc/whatever, that triggers the event on collision, but i dont know i this is the best way, or if there is any easier and better way to do this? Does unity have a function for this?

Do it like have already thought for now. That would give you a trigger based on proximity only. You need to think of how you want the enemy to behave and if it has a motive which will require a different action when it gets close but in that case proximity could still be a useful trigger for a different action. Perhaps polling the distance until much closer etc.