Bathroom layout possible like this - distance from toilet to drainpipe

Where the downpipe is drawn, it cannot be there. That is, of course, pretty amateurish of the bathroom planner.

What are we even talking about here: a modernization, or is the house just planned and no decisions have been made yet? - why are you only discussing based on the bathroom planner’s drawing and not the architect’s plan or the survey? Furthermore, I generally advise all builders against picking out only individual points where they get stuck to ask about. There are some experienced plan readers here. Whoever sees the whole picture can also suggest improvements for such points that the questioner hasn’t even noticed yet will also cause problems.