You need a Palatino with proper OpenType support, alternatively you can use TeX Gyre Pagella (which is true Palatino by Zapf, and further opentypified by GUST) which is included in TeXlive.
\documentclass{article}
\usepackage{fontspec}
\setmainfont[Numbers=OldStyle]{TeX Gyre Pagella}
\begin{document}
Text 12345.
\end{document}
Here's a list of common (CTAN available) roman(*) type1 fonts, mostly assuming T1 font encoding ...
ADF Baskervald - no
ADF Berenis - native, use package option osf
ADF Electrum - native, use package option osf
ADF Romande - ONLY osf, i.e., no lining figures
ADF Venturis - native, use package option osf
ADF Venturis 2 - no
ADF Venturis Old - osf standard, lining in titling fonts (see documentation for access)
Adobe Minion Pro - native, use package option textosf or similar
AE - try \oldstylenums, otherwise access directly via TS1 encoding
Antykwa Poltawskiego - via small caps
Antykwa Torunska - via small caps
Augie - no
Auriocus Kalligraphicus (etc.) - ONLY osf, i.e., no lining figures
Bera Serif - no
Bitstream Charter - no
Computer Modern - try \oldstylenums, otherwise access directly via TS1 encoding
CM Bright - try \oldstylenums, otherwise access directly via TS1 encoding
CM Dunhill - try \oldstylenums, otherwise access directly via TS1 encoding
CM Fibonacci - try \oldstylenums, otherwise access directly via TS1 encoding
Concrete - try \oldstylenums, otherwise access directly via TS1 encoding
Day Roman & Day Roman S - ONLY osf, i.e., no lining figures
DejaVu - no
Droid - no
European Modern - try \oldstylenums, otherwise access directly via TS1 encoding
GFS Artemisia - via small caps
GFS Bodoni - via small caps
GFS Didot - via small caps
GFS Neohellenic - via small caps
Gyre Bonum - try \oldstylenums, otherwise access directly via TS1 encoding
Gyre Pagella - try \oldstylenums, otherwise access directly via TS1 encoding
Gyre Schola - try \oldstylenums, otherwise access directly via TS1 encoding
Gyre Termes - try \oldstylenums, otherwise access directly via TS1 encoding
Iwona - try \oldstylenums, otherwise access directly via TS1 encoding
JAM Times - no
Kurier - try \oldstylenums, otherwise access directly via TS1 encoding
Kerkis - try \oldstylenums, otherwise access directly via TS1 encoding
Kepler Project fonts - native, use package option oldstylenums
Latin Modern with `lmodern` - try \oldstylenums, otherwise access directly via TS1 encoding
Latin Modern with `cfr-lm` - native (proportional osf), see documentation for other options
Libertine Legacy (type1) - native, use package option osf
B&H Lucida Bright - try \oldstylenums, otherwise access directly via TS1 encoding
New Century Schoolbook - no
Palatino - without mathpazo: \renewcommand*\rmdefault{pplj}
Paratype PT Serif - no
PXFonts - try \oldstylenums, otherwise access directly via TS1 encoding
Times Roman - faked smallcaps & oldstyle (TS1) figures via txfonts package
TXFonts - per comment attached to Times Roman
URW Garamond - no
Uncial - no
URW Antiqua - no
URW Bookman - no
URW Nimbus - try \oldstylenums, otherwise access directly via TS1 encoding
Adobe Utopia - via small caps
Zapf Chancery - no
(*) i.e., for fonts you might set up in \rmdefault
. Just to round things out, I've thrown in some examples -- augie, iwona, uncial, etc -- that on first blush don't fit this mould.
Best Answer
Educated guess: enclose the text block in a group and switch to the
fxl
font.