So rather the standard of the municipality with its own notary. I don’t know it any other way either - a municipality usually doesn’t go through the hassle with every single notary for a new development area
The standard here is the buyer’s right. It doesn’t matter which notary in the region he goes to. He has to take care of each contract individually. I don’t know it any other way :)
A municipality cannot dictate the notary. However, it can more or less choose the buyers, which gives some leeway. A municipality can also set criteria for the land buyers if they are "entitled" (locals, families...)