Planning for the development of a hillside property - experiences?

Hello, my name is David, I am 23 years old. Last year I purchased my building plot, a hillside property of 1000 square meters, which I have now paid 90 percent for, and now I would like to start building. My personal budget is 300,000 euros. My question regarding planning is: is the outdoor area planned by the architect as well, and does the planning of the outdoor area appear in the building application? Because retaining walls need to be constructed whose structural calculations must be done. Or is that planned by the earthworks company and in the building application only the plan for the house appears. Best regards, David

The slope is included in the statistics. The basis was, among other things, the report from the geologist. The statics are included in the construction plan (e.g. thickness of the wall on the slope side, ceiling). The slope with retaining wall was drawn in our building application; whether that is necessary or just because of the existing structure, I do not know.

With 300,000 including incidental building costs, you won't get far on a slope location. Unless you have masons, plumbers, and electricians in your circle of friends and you want to enjoy building for the next 2 years.