I'm sure it's normal to want a completely flat chest, and it's not entirely uncommon for very skinny cis guys to have that as far as from what I've seen. But at healthy weight and heavier guys tend to have a little bit of fat (or more) and/or pecs. But I think the desire to have a completely flat chest is normal nontheless. However, if it's possible to achieve with binders in a safe way, I have no idea. Possibly if you already have a small chest, but otherwise I'm not sure if there is a way. My best advice would be to layer your clothes over your regular binder to give a flatter appearance when dressed. I used to do that in my past and it worked well (I had about B-cup, but I'm sure it can work with bigger chests as well, at least to a certain point). I did also very much want a completely flat chest, but over time I came to like the idea of it not looking quite that flat. What helped me re-think my desire was that because I wasn't super skinny, I thought an almost flat chest would look more proportionate to the rest of my body. I was quite anxious about there being a bit of a lump on my chest even with binder, so that was why I decided to re-think my desire, and then I got a lot less anxious about that.