How do I search by multiple tags?
As I finished writing my own question, I tried another combination, tag:&lt;tag0&gt; tag:&lt;tag1&gt;, and it worked! Seems like it's an implicit &quot;AND&quot; when you use it like this.
You can also apply boolean logic in Spotlight/Finder:

tag:&lt;tag1&gt; OR tag:&lt;tag2&gt;
tag:&lt;tag3&gt; AND &lt;tag:4&gt;
NOT tag:&lt;tag5&gt;