At least with some ThinkPad with discrete GPUs they put a BIOS option for toggling whether to use integrated graphics, discrete graphics or both which means you

At least with some ThinkPad with discrete GPUs they put a BIOS option for toggling whether to use integrated graphics, discrete graphics or both which means you can avoid Optimus if you want. I've had other laptops without such an option and then you have to deal with Optimus or some other workaround. It's not perfect though because often video outputs will be routed through one card or the other so if you want to use the Displayport out you have to use discrete graphics.