I think you might not understand what a responsive theme does. A responsive theme changes the layout depending upon the size of the screen. For example, if the site has a sidebar to the right on a desktop computer, the sidebar would shift to the bottom on a cell phone. The menu will usually change to either a drop down or a hamburger menu, i.e., some sort of mobile menu.
What you are describing is a fixed layout. That is, the layout remains the same on a desktop or a cell phone. A sidebar on the right will still remain on the right, and the menu doesn’t change format. The problem with a fixed layout is that your visitors will have to zoom in and scroll sideways to be able to read the site, which is usually very inconvenient. If you still want a fixed layout, you can go to the WordPress theme repository, click on the Feature Filter link, and check the box labeled Fixed Layout.
You can also search for a Fluid Layout theme. A fluid layout is like a fixed width layout, but the widths of the elements will change as the screen size gets narrower. The elements will stay in their same relative position. However, with a Fluid Layout, things start looking very squished together at narrow screen widths.