Certainly, we can. We (obviously) are not actually hiring any actors or doing any filming.
However, if you hire someone who already has those skillsets, you aren't starting from scratch. So, in our fantasy production, seeing examples of what the actors can do (because they've already done something adjacent to what we want in another film production) helps us to visualize what we would be getting in our production.
If you hire someone like Jeremy Renner (well, not this second, but in general....) and ask him to hit certain marks and do certain moves on film...he will do that. He has a lot of training, a lot of experience, and he's fast. So he can get himself into the correct position on set and get the director the shot they want, pretty much as good as any stunt double. Someone who is new to action films....can't do that, probably. They will need to work a lot harder to make more basic stunt choreography work.
If you want to film a sword fight, you can hire someone like Christopher Lee (again, obviously not any more...) who has most certainly done that many, many times on film and knows how to do it well and make it look good. Or, you can hire a beginner, and train them in the exact sequence they will be doing for your film. Adjacent skill sets are fine - Sebastian Stan did a lot of knife flipping as Bucky Barnes, and (presumably) a lot of drumstick twirling as Tommy Lee. Both skills require similar dexterity. Summer Glau's dance training lent itself to her fight training choreography. But if you hire someone who typically plays 'the cute love interest' and put them into an action sequence, you might get some cringey fight scenes.
So, yes, we can 'think outside the box' and choose someone who has never done any fight scenes on film before, with the understanding that we'll make it work. There is no rule saying you have to pick someone who has done this before. But that does make it a bit harder to visualize what type of fight scene we'd be getting. This project has very, very few storyboards thus far...and part of the reason for that is that it takes a lot of time and effort to generate a storyboard! But I think that would be one way to convey what an action sequence would look like in the absence of existing footage of the actor 'in action', as it were.