Most of these wishes should be clarified before signing the contract: sewer works, ceiling height, roof overhang, roller shutters, special patio doors, additional sockets are foreseeable and definitely belong in the offer phase. Different offers are also hard to compare if they contain completely different standards.
If you know all that beforehand, that's nice.
For example, we only decided on the lift-and-slide doors later. The roof overhang never really caught our attention before, and regarding the height of the stories, we previously thought the standard would be enough for us. Like many other builders, our requirements/wishes changed again during the planning phase.
We also had additional sockets etc. on our radar and had, for example, planned a "supplementary" budget for the electrical work beyond the standard in the construction service description.
Ultimately, you can also decide on these additional things after signing or cancel them again if they seem too expensive or the financing depends on it. At least, we had that documented in writing.
For us, that's absolutely okay since we are still a bit below our budget limit for the house :)