WMP (Windows Media Player), which is included in XP, can play DVD discs if you install the mpeg2 codec. Or you can use pretty much any standalone media player which you prefer. MPC-HC, VLC, GOM, PotPlayer, etc. (all free).
For Blu-Ray support, you are pretty much out of luck. From a software standpoint, the only real options are PowerDVD or WinDVD. VLC doesn't officially support Blu-Ray. Also, I don't recall specifics, but I seem to recall that Blu-Ray support in XP was sketchy at best. You do need HDCP compliant hardware, so a compliant video card with HDMI output and a monitor using HDMI input. To make matters worse, you would need PowerDVD or WinDVD as ntoed above, but I doubt the new versions will even run on XP. Which means you would have to use an old version, which would be a security risk and wouldn't contain all of the encryption types/codes needed to play any discs newer than when that version of the software was released.