If nothing is downloaded, is there anything left behind on the hard drive. Say viewing a video or reading an article.
With the Tor Browser? Ideally nothing.
New bugs are unfortunately found from time to time and then fixed. One current example is the clipboard “cache”.
If disk leaks are a problem in your threat model, use Tails. It gives you the guarantee that nothing will be written on disks, unless explicitly done as a user action.