How can I download and install windows xp within windows 10?
Microsoft ended XP downloads many years ago.
And we can not recommend any sites to download XP from.
XP still does not come for free.
A lot of XP downloads are compromised by having embedded Malware included with it.
You would not be able to do a dual boot of 10 and XP as you would find that the Windows 10 Manufacturer of that machine would not support XP or have XP drivers available for it.