I am a PHP developer new to CodeIgniter. Is CI Wiz a good way to learn CI4?

Yes, and this is one of CI Wiz's more underrated use cases. Reading CI4 documentation gives you the concepts; reading CI4 code generated to a consistent standard gives you working patterns to imitate. A CI Wiz-generated app shows you in practice how entities and models relate, how route groups are organized, how form validation is structured in CI4 (not CI3 style), how CSRF protection works in forms, and how the view layer is built with template inheritance. Each of those is a topic that trips up people migrating from CI3 or from other frameworks. If you have PHP OOP experience, generating a two- or three-table app and reading through the output is a faster CI4 on-ramp than working through the docs in sequence. The generated code is intentionally clean and follows documented patterns — it is meant to be readable.