Variants are virtual copies of your image files. Once you are done imaging and ready to edit, the first step is to create variants before you crop or modify any image. That way, you will create a copy in Capture One that you can adjust while leaving a master file untouched.

How to create variants?

First, select your images (cmd+a to select all).
Then right click + select Clone Variant OR go to Image –> Clone Variant
New variant will only create a copy of your image without the settings (LCC, white balance, etc.) For image preservation purposes and consistency only use the Clone Variant function.

Your variant copy will appear in the menu on the right.
#1 is the primary variant, left untouched for preservation purposes.
#2 is the secondary variant, that can be used to create cropped derivatives.
Capture One CH allows you to create as many variants as needed.

If, after having selected all your images it only create variants for one image only, you need to double check if the document icon on the top right hand corner is highlighted. Indeed, if it is not highlighted, adjustments only apply to the primary variant.

Additionally, Capture One allows you to select by variants for editing or exporting all images at once.
Right click + Select by Same > Variant Position.