From what I have been able to find in the ArcGIS Pro documentation via Google search for one-to-many table joins the only method other than using python (which I am not great at) would be the Query Table tool.
When I use the Query Table tool the output generates a temporary polygon feature class but whenever I try and view the attribute table it ends up with a spinning circle of doom and never loads. There is no error code associated so I'm not sure how to hunt down the problem.
Does anyone know how I might trouble-shoot this issue or if there is another way to do a one-to-many join in ArcGIS Pro?