Smaller plot - Is something feasible from it?

Especially because the broker casually mentioned again today that an estimated height increase of 2 m from front to back is to be expected...

Does front to back mean... from the top of the plan to the bottom or vice versa, or from left to right on the plan or vice versa?

No matter what, this is already the second hard pill you really want to swallow? 2 m is really a lot, especially because, due to the small plot, you can't work with slopes. Overcoming 2 m with L-shaped retaining walls in such a small space is really bad and expensive.

In addition, the small plot will inherently cost you more in terms of development/planning.
Example:
- Excavated material cannot be stored sideways
- Crane placement with fencing would be mandatory
- Everything must be removed immediately
- If a basement is involved, sheet piling walls become mandatory. 10 m = 10k€
- and who knows what else...

the deviation from the standard

7m * 12m does not automatically mean deviation from the standard. A ready-made townhouse floor plan fits there already, with the option, not the obligation, to install more windows.

that a estimated height increase of 2 m from front to back must be expected ...

Sounds concerning, but does not have to be. It could even offer possibilities for living rooms in the basement. Further discussion only makes sense if the development plan with textual regulations, especially eaves, ridge and plinth heights, and the exact topography of the property are known.