OneEffGeof

I have an STL file that I have previously sliced with a 3.xxx version of Cura. I currently have Cura 4.0. My problem is that I don't have the original file I downloaded from Thingaverse some time ago and I can't seem to find it again. The current sliced version that I have is too small for what I want to do and one can't apparently edit a sliced file )I gather). Is there a way I can edit this file again using Cura? I tried to use Fusion 360 based on a tip from someone on Reddit but that won't download so I am stuck. Thanx ahead of time for the help.