Seller says that for my size 185cm i should buy 18 M size frame. That 19.5 L is for height over 190cm. I have doubts, can you look at geometry chart and advise me if it is ok?

I'm 188 cm and would be looking for the XL that they don't seem to offer; I would be looking for an effective top tube at least 640-650 mm with a reach of at least 470mm. Depending on how long your legs are, I would be wary of that you could get the saddle high enough without running an unusually long seat post

At 190 cm I would find a bigger frame!