Custom checkbox/menu fields Limit

Summary:

We want to know if there is any limit for custom checkbox and menu fields.

Content (required):

Our customer has many different question forms, each one with specific fields and many of them are menu fields.

We know that there is a indexed fields limit for incidents (30 if not mistaken). I've heard that menu custom fields count automatically as an indexed field for that limit, can anyone confirm that information? Would a boolean field also count as indexed?

Version (include the version you are using, if applicable):

Code Snippet (add any code snippets that support your topic, if applicable):