The ROTATE command rotates an object around a base point. The ROTATE3D command rotates an object around a 3-dimensional axis.
In AutoCAD MEP 2023 toolset, you can use ROTATE3D to rotate fittings around a specified axis and connection point. However, a quicker and easier alternative is Rotate grips. In plan or isometric views, you can use Rotate grips to rotate both fittings and inline parts. The grips adjust connected objects and maintain their connectivity whenever possible.