Searching for the "full movie" of on the Internet Archive often results in finding user-uploaded copies that vary in quality or are frequently removed due to copyright compliance. While some archival footage or soundtracks might exist there, it is not an official distribution channel.
Yash Raj Films has uploaded the full movie on YouTube (often ad-supported or for rental). Search for "Veer-Zaara Full Movie YRF." This is a free (with ads) or low-cost rental that beats Archive.org quality by a hundredfold. veer zaara internet archive full