yes, the easiest way to draw 2D in sketchup is probably to keep it in a group, Inplace where the detail is supposed to go, so, that you can reference sizes in main geometry, and then have that group containing tags in a Tag-folder used for details. You can have specific scenes for the details, and can easily have it separated from the main model. That main model has scenes where the details folder is hidden.
But the principles of inference locking works also on geometry that are not" well placed" related to the axis system
This is not to say that this is the best method. I too would like to do my building details in Layout. It´s just that, for now, I find inference in LO lacking compared to what I´m used to in SU, and I can’t help trying to do things the sketchup way when I work in Layout.