In Unity, how can I render borders of provinces from a colored province map in a grand strategy game?

I am kind of a beginner of Unity.

I am trying do work on a grand strategy game. I already have a province map, colored by unique rgba for each province, looks like something below:

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I know that the province map is kind of a look up map for province id. But when I obverse the paradox strategy games, I notice that they have render borders differently for the provinces and nations. For example, in the CK3, the Baron collars are separated with dotted lines, and the kingdoms are separated with enhanced yellow lines.

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I thought they have some other maps or files containing those information, so I went to read their dev diary, and I find that all province shape information are stored in the province map.

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So, my question is:

Is there any way in Unity3D to create those different borders with some shader and some province map such those given above?