In Australia at least we need to submit development approvals which are public for some time.
As part of these approvals there will be floor plans and architectural drawings. They won't be enough to build off (usually), but they're a great source of inspiration it you're looking for ideas, costings, and what your local council is willing to approve.
This is true in most parts of the USA as well. In the State of Florida where I live, all drawings and plans become public record and these would definitely be enough to build. This is because all drawings used to build are required to be submitted. This includes details like engineering drawings and calculations and roof truss layout.
They are still protected by copyright but I'm not sure if it's relevant in the context of using the same plans to build a house. Copyright is meant to protect against copying and derivative works not how the information is used.
In Australia at least we need to submit development approvals which are public for some time.
As part of these approvals there will be floor plans and architectural drawings. They won't be enough to build off (usually), but they're a great source of inspiration it you're looking for ideas, costings, and what your local council is willing to approve.