You can add custom meta tags to funnel and website pages by clicking SEO Meta Data icon at the top of the builder.

These tags are used by search engines to convey information and instructions to the search engine. 

For reference, here is a list of meta tags Google supports:

Example: you can use the following meta tag to tell search engines not to index a particular page by naming a new custom meta tag "robots" and the content as "noindex" as shown below.