setmathfont{Math Caligraphic Alphabet}[Scale=MatchLowercase,range={scr,bfscr}]

setmathfont{Math Caligraphic Alphabet}[Scale=MatchLowercase,range={scr,bfscr,bb}]

$mathscr{A}mathscr{B}mathscr{C}$ % my cal letters

$mathbb{A}mathbb{B}mathbb{C}$   % STIX Two bb letters

setmathfont{Math Caligraphic Alphabet}[range="211D]

setmathfont[range="211D,"2124]{Math Caligraphic Alphabet}

! The key 'fontspec-opentype/"2124' is unknown and is being ignored.
!
! See the LaTeX3 documentation for further information.
!
! For immediate help type H <return>.
!...............................................

l.108 ...e="211D,"2124]{Math Caligraphic Alphabet}

setmathfont[range={"211D,"2124}]{Math Caligraphic Alphabet}