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How to plot the 3D-boundary of California or other states

I can get the postion with this code

pos = First[
  Flatten[#, 1] & /@ 
   First[Entity[
      "AdministrativeDivision", {"California", "UnitedStates"}][
     EntityProperty["AdministrativeDivision", "Polygon"]]]]

You can see the postion in the map

GeoListPlot[GeoPosition[pos]]

Mathematica graphics

I can get their elevation

pos = First[
  Flatten[#, 1] & /@ 
   First[Entity[
      "AdministrativeDivision", {"California", "UnitedStates"}][
     EntityProperty["AdministrativeDivision", "Polygon"]]]]

Then I get the data

data = Flatten /@ Transpose[{pos, List /@ eleData}]

I can plot its discrete plot

ListPointPlot3D[data]

Mathematica graphics

But how to connected those discrete points to get a smooth boundary?