Can I build my models in a schema other than my target schema or split my models across multiple schemas?

Yes! Use the schema configuration in your dbt_project.yml file, or using a config block:

dbt_project.yml

name: jaffle_shop
...

models:
  jaffle_shop:
    marketing:
      schema: marketing # seeds in the `models/mapping/ subdirectory will use the marketing schema

models/customers.sql

{{
  config(
    schema='core'
  )
}}