New construction options fall within a very wide range. Your place within that range will depend on your price range, builder selection, subdivision, desired customization, lot availability, and your preferences.
At one end of the spectrum is the spec house (nicknamed for speculation). The builder, who speculates that the right buyer will come along, plans and starts construction before there is a real buyer. Almost all decisions are made by the builder: what floor plan is built on the lot, how the home is decorated, and what amenities are included. The builder begins construction and sometimes completes the home before there is a buyer. If you buy a spec home before the builder completes it, you sometimes may choose a few items not yet in the home. This home is usually built relatively quickly.
At the other end is the custom home. Here most of the decisions are made by you: what lot to buy, which builder to hire, floor plan, specifications, decorating and amenities. Once these decisions are made, the builder will bid the project based upon cost and availability of materials, subcontractor fees, and the fees to oversee the project. This type of home usually takes longer to build because you are involved in every phase of the project.
In between are many variations. Typically, a builder will have numerous lots in a subdivision and a wide variety of floor plans. You select a floor plan and then view lot inventory. Your choices are made from a builder list of available upgrades, decorations, and amenities. Add-ons or changes in construction details will move this project closer to either one end of the customization spectrum or the other. The more you change the builder's existing plans, the more customized the house becomes and the longer it will take to build.