This is a paid asset, but now you can download Simple Particle Scaler Free.
Detail this asset from Unity Store: Original Link
Simple Particle Scaler v1.1.3 (Latest version)
Simple Particle Scaler makes scaling particles easy, simply select one or multiple particles in your hierarchy and scale with a click of a button. This tool also enabled you to save prefabs of your newly scaled particles, so you don’t have to drag each one separately to your project.
∙ Scale Multiple Particle System
Scales all selected shuriken particle systems
∙ Save Multiple Prefabs
Creates prefabs from selected GameObjects
The tool is located in “Window/Simple Particle Scale”
Demo video uses asset Liquid Particles
Compatible with Unity 5.1 up to new versions of Unity(2020+)
Support available for assistance if any problems should occur.