Soundness in clang SA

Of course you can make any static analysis reports just some very specific
bug(s) that are already known, so the answer to your question is yes. But that's
probably not what you were asking about.

If you want the analysis to only report genuine bugs, you
may want to consider using fuzzers instead, like AFL or libFuzzer.
They are not guaranteed not to report false positives, as the environment
under which the subject program is fuzzed may be different from the actual
deployment environment, but at least they may be closer to what you
have in mind.