Edit:
Never mind! After comparing the Firebolt cantrip, which upgrades its damage and the Eldritch Blast cantrip, which upgrades the amount of targets, I was actually able to find it, so for everyone interested, here goes:
The property I was looking for is called "LevelMapValue".
You can find the game's LevelMapValues by opening the "Uuid Object Editor" where it is located in the following folder path:
Shared -> Levelmaps -> LevelMapValues
So you can either copy one of the existing ones by right clicking, then selecting "Create derived in" and then selecting your own project, or simply navigate to that folder in your project and create one from scratch.
Still, thanks to anyone who was about to answer!

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Hi everyone!
I'm finally trying myself at modding and as a first little exercise I want to create a cantrip. I've learned almost all I need to get started, but there's one last piece of info, I could not figure out so far:
What property is responsible for upgrading cantrips at character levels 5 and 10?
Example: The Firebolt cantrip deals 1d10 points of fire damage by default, then gets an additional d10 at character levels 5 and 10 each for a total of 2d10 and 3d10 respectively.
So my questions:
1. Which property "tells" the cantrip to upgrade at character levels 5 and 10?
2. Which property (if it is a different one) defines what those upgrades should look like (i.e. additional damage dice, additional targets, etc.)?
If somebody has already figured that out and could tell me, or if there already is a post, which explains that (I didn't find any) and you could point me to it, that would be super appreciated.
Thanks in advance to anyone who can help!