This also depends on who you refer to as a client - if you’re consulting, the best thing to do is up front set the expectation for your deliverables with the client.
Usually if you include a “sample” brochure of how you work explaining the difference to these things (Because to some people a CAD rendering is just as good as a hand sketch if they don’t understand what they’re looking at) you can say “this price will get you 5 concept sketches” and then that starts the dialog of whether or not it’s correct and you can go from there.
You want to avoid the mistake of assuming your client knows what a “Rendering” is and showing up with a bunch of fancy digital sketches when that wasn’t what they were intending on looking at or wanted to see.
I’m in the corporate world, so your internal audience is much closer to what Yo said - simple sketches are good enough to communicate some design details and intent, fancy sketches are nicer but not always needed when you’re just trying to get a concept across, especially to engineering or marketing, and lots of times sketches aren’t good enough at all, you really want a quick prototype to show how something feels in the hand, get a real idea of the size, etc - especially when dealing with handheld products.