Maximum number of participants added via webinar add-on won't be applicable for meeting?

You'll need to check your specific account. In Zoom Admin Portal, navigate to Account Management -> Account Profile and you should be able to see what the standard meeting capacity on your plan is:

Beyond that, you may have 'Large Meeting 500', 'Large Meeting 1000', etc licenses for individual users that can be added to the meeting host's account for increased capacity.

But yes, webinar capacity and meeting capacity are independent.