Are there rules for forming adjectives from names? [duplicate]

I may not be using the right terms for what I'm asking, but for example, "Cartesian" is an adjective derived from Descartes' name, and "Dickensian" is an adjective derived from Charles Dickens' name, both of which are used to describe things that are related to the particular person they refer to. Are there rules (even loose rules) for how such adjectives are created, or is it more of an art than a science? Is there a special name for such adjectives (like a "demonym" is a noun for people from a particular place)?

Thank you in advance for any help. Please let me know if you'd like any clarification of what I'm asking!

Edit

And if there aren't rules for this, what are the most common suffixes used, and what are examples of such suffixes?

I think that it's a case of "if it works, use it". It obviously doesn't work with some names, e.g. Kafka: "Kafkaian" doesn't sound right (and I wouldn't know how to make it sound right), so we use "Kafkaesque" instead.