This simple exe reads an accompanying txt file, taking the exe to run from the first line and the parameters to pass as an optional second line.

Ways to use:
1) STEAM: Add the launch options in Steam.
Starfield with SFSE example:
Launch options: "C:\Program Files (x86)\Steam\steamapps\common\Starfield\exeLauncher.exe" %COMMAND%
exeLauncher.txt put: sfse_loader.exe

Now Starfield launches SFSE from Steam without further shenanigans.

OR
2) Put this in the game folder next to the real exe and run it instead.
Warframe example:
1st line of txt: Warframe.x64.exe
2nd line of txt: -fullscreen:0 -graphicsDriver:dx12 -gpuPreference:2 -cluster:public -language:en -clienttype:Steam -deferred:1

Now Warframe skips the launcher. Obviously this means it can't check for a patch first, so only works if you're up to date.

OR
3) You could straight up replace a launcher's exe with this file.

There are plenty of other ways to do something like this, but I wrote this for my specific purposes at the time.
It does NOT handle paths to exes, as far as I remember, so it has to be in the same folder as the exe you're starting. If Steam sets the working directory to something else on launch, that'll cause problems. The Warframe example above doesn't work from Steam because it starts in the Tools folder.

Could I fix that? Yeah. Will I? Unlikely. Provided as-is in case someone has a use.