Law can shift an extravagant picture into a hypothetical construction. The listener then understands that the sentence is not necessarily reporting an actual occurrence.
For example, “Even if the sea of his generosity dried up, his gifts would not end” is a teaching illustration. It imagines a condition to intensify generosity rather than to report a literal sea drying up.
Because law also serves other grammatical functions, its mere occurrence does not prove acceptable ghulūw. The hypothetical relation must contribute meaningfully to the rhetorical effect.