Yes, you can dynamically set dates in filters, but not by typing {{today}} directly.
Two ways to do it:
1. In Zapier Tables: Use the "is within" rule → select dynamic ranges like "Last 7 days" or "This calendar week". Documentation Link
2. In Filter by Zapier: Add a Formatter by Zapier step → Date/Time → Format → set Input to "Current time" → then compare that output to your date field. Documentation Link
If you're still running into issues after trying these steps, drop a screenshot of the error and a quick description of what your Zap is doing, happy to take a look!
And if you'd rather just get it sorted quickly, I offer a free 20-min Zapier troubleshooting call. Book it under Resources on my Zapier Directory profile: https://zapier.com/partnerdirectory/automatemybiz