Is there a fee for using Siri on iPhone?

As lobsterghost1 noted, there is no fee for Siri. However, if you opt for the paid version of ChatGPT, which is between you and ChatGPT, you can link that version to Apple Intelligence. If you don't have the paid version, Apple Intelligence will use the free version.

Andru555 wrote:

there will be a fee for using the siri feature?

No. There is no fee to use Siri.