How we (used to) structure our dbt projects

Thanks. I am new to the area, and I assume that a BI tool can be used to select a rollup from a list of available rollups, but that it does not in itself calculate the rollup. Sounds like I am wrong about that. Can you provide an example, i.e. a BI tool that is smart enough to create a rollup on it’s own? How does it do it? Does it create the SQL query to generate it?