For anyone that is returning to figure out how to scale a niagara emitter/system, I have made a script that fixes scale for sprite and mesh and it also fixes velocity for the particles.
This was made in UE 5.2, but will probably work with any UE 5+ project.
IMPORTANT!
You need to put the script node at the bottom of “Particle Spawn”. (you need to drag the node in from the content browser “Ctrl+Space”)
If you are struggling with the convert node then look at the previous reply!