Brachylog, 14 bytes

{⊇Ċz-ᵐ^₂ᵐ+√}ᶠ⌋

Try it online!

Boring and straightforward.

Brachylog, 14 bytes

{⊇Ċz-ᵐ^₂ᵐ+√}ᶠ⌋

Try it online!

Boring and straightforward.

             ⌋    The output is the minimum of
{          }ᶠ     every possible
          √       square root of
         +        a sum of
      ^₂ᵐ         the squares of
    -ᵐ            the differences between
   z              the coordinates for each axis
 ⊇                for a sublist of the input
  Ċ               containing two elements.