There are no rules, but plenty of inspiration available.
Card layouts are commonly called "spreads" and can include any number of cards -- 3, 5, 7, 12 whatever you want. Any number.
There are spreads for all kinds of purposes. There are some I like. But a lot of experienced readers will tell you they don't use spreads. They won't even necessarily even pre-decide how many cards to pull.
The more you get in touch with your intuition, the less you might reach for structure and guardrails.
But as you learn, these spreads can be helpful. They help "assign" a single focus or role to each card. And some people like that structure, so they continue using it. :)