Output a Pyramid (or Highway)

05AB1E, 11 bytes

F²γN>×J}».C

Uses the 05AB1E encoding. Try it online!

05AB1E, 9 bytes

γ².D)ƶJ.C

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γ was, in no short amount, inspired by Adnan's answer; but S would also work.

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γ          # Split into runs.    | ['0','-','0']
 ².D)      # Push n times.       | [['0','-','0'],['0','-','0'],['0','-','0']]
     ƶ     # Lift by index.      | [['0','-','0'],['00','---','00'],['000','---','000']]
      J    # Inner join.         | ['0-0','00--00','000---000']
       .C  # Center.             | Expected output.

Jelly, 14 13 bytes

LH×Ḷ}Ṛ⁶ẋżxЀY

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How it works

LH×Ḷ}Ṛ⁶ẋżxЀY  Main link. Arguments: s (string), n (integer)

L              Get the length l of s.
 H             Halve it, yielding l/2.
   Ḷ}          Unlength right; yield [0, ... n-1].
  ×            Compute [0, l/2, ..., l(n-1)/2].
     Ṛ         Reverse; yield [l(n-1)/2, ..., l/2, 0].
      ⁶ẋ       Space repeat; create string of that many spaces.
         xЀ   Repeat in-place each; repeat the individual characters of s
               1, ..., n times, yielding an array of n strings.
        ż      Zipwith; pair the k-th string of spaces with the k-th string of 
               repeated characters of s.
            Y  Sepatate the resulting pairs by linefeeds.