Yes! Well... it depends how you are defining interior design. Are you thinking about finishes and furnishings? Or about the design of the interior space; how spaces relate to one another, circulation, flow, function? If you are speaking of design, and not decoration, please consult with an interior designer at the same time as the architect, or before. In my experience, interior designers think on a smaller, function based level; architects are about the big picture. An interior designer should ask you how you live. This question helps to guide design because they will consider your particular needs. Also, consult with a kitchen and bath designer before finalizing house plans. Most times, interior designers (and kitchen and bath designers) work with what they are given. Sometimes it is a fixed space. Sometimes a wall or two can be taken down. And we do the best we can with what we've got. BUT, many times, a designer dealing with interior spaces wishes they were consulted before plans were set in stone (so to speak). Sometimes, it is the little things that make a big difference in function.

Design style is an overall group of characteristic design elements that are generally accepted to collectively define a particular look (e.g. mid-century modern, French country, etc.) whereas theme is typically used to identify a specific motif (e.g. Disney kids' bedroom, man cave with sports theme, etc.).

interior designer

Give the idea of decorating it as living and dining room.