where exactly is the difference for the real estate transfer tax, whether we buy a property from a private individual or through a broker?
In terms of the real estate transfer tax, there is no difference.
Since it fits the thread title: Is it possible to deduct the artistically designed ornamental garden including pond and fish from the purchase price when buying a single-family house with a garden, in order to calculate the real estate transfer tax?
There is no difference regarding the real estate transfer tax.
Since it fits the thread title:
Can you deduct the artfully designed ornamental garden including pond and fish from the purchase price when buying a single-family house with a garden to calculate the real estate transfer tax?
You can have many things deducted from the purchase price. However, this must also be reflected in the notarized purchase price (for example, in the last house we deducted the kitchen and had it paid for separately by our buyers). The downside for the financing bank (and you) is that a lower purchase price also results in a lower lending value and market value (possibly worse conditions due to higher risk).
Sorry for the silly question but where exactly is the difference in real estate transfer tax whether we buy a plot of land from a private person or through a broker?
There is a difference whether you buy from a private person and then have a house built on it, or whether you buy the plot and the construction of the house from a single source (property developer). In the first case, you pay the tax on the plot, in the second case on the plot and the house. That is then significantly more.
But that somehow did not relate to the specific question. As long as no statement is made there, it is groping in the dark as to what the OP intends with the question.