Go to a show house with 120-130m2 and check if that is okay for you. For me, back then, it was important not to build too small, so I gave up the basement for cost reasons. I wanted more living space on one level. But the house also has to be in a realistic (size) proportion to the plot. On YouTube, [HausbauHelden] recently posted a video where the topic "Aktionshaus" is discussed.