Steam version.
Open location where the game is on Epic version, rename the exe to RebelGalaxySteam.exe then run the game. The trainer will recognize it and activate cheats.
That might work....if the Epic Games store thing actually downloaded the games directly to your computer like Steam. But they don't. As I suspect, 99% of the people asking for the trainer for epic games has downloaded it during the free game weekend for it.
"But unknown noob, how do you know they don't put it directly on your computer?" Simple my good but misleading friend, When I right click on the shortcuts on my desktop, one, there is no option for opening the files location, and two, Properties of the shortcut tells me its an internet shortcut. Which tells me that either they are being nice to our HD's or they might yank the games at some point, so we have to actually purchase them.