How to make a projectile curve after firing?

I wasnt trying to scare you :o) but there is still math involved in moving things around in a 3d environment. Curves are easy enough they are basically a plotted graph that you can use to get values based on certain input.

As for your dynamic sling shot power … the “normalized curve” (sorry its a made up name) example will work perfectly for that … you just need to adjust the 3 parameters (maxHeight, maxDistance and maxTime) based on power of the shot.

You might get away with using a lerp for that … another math based blueprint node that would allow you to create a Linear intERPolation for each parameter that basically increases those 3 values linearly based on the power of the shot … so look at LERP too.

HTH