Hi Panda,
If you modify your Visual Studio, the old workloads you have installed don’t need to be reinstalled unless the old workloads are damaged.
After clicking on the “Modify”, you will open the following page. As the picture shows, the old workloads are checked, which means you have these workloads installed on your computer.
If there is any misunderstanding, please feel free to let me know.
Sincerely,
Anna