For any individual preset you may override general defaults by selecting special parameters of presets themselves.
This can be done when you create new preset with Crop Setup Panel. There are Fixed Pixel Export Width and Upscale smaller images options.
Fixed Pixel Export Width - If this field is zero, the program exports crop as large (or as small) as it was cut from the photo. If this field is not zero the program downscale larger crops to selected size.
Upscale smaller images - Fixed Pixel Export Width is not zero and this option is active - the program upscales smaller crops and downscale larger crops to selected size.