Just answer to make sure that others have not turned their back on the first visible answer / comment from @Ahmedilyas, which says this is not possible.
My scenario was different, I wanted to quickly use the additional "Architecture" function found in Enterprise, which I did not have in my version of VS 2017 Professional.
To the point ... YES you can . Just open the visual studio installer, and if you have 2017, you should have an option available to install the Enterprise version, and it will NOT overwrite the previous installation. You have the choice to add features, select custom installation folders, etc.
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