CA FTB says....
Attachments to your tax return.
Do I need to attach a copy of federal Form 1040 or 1040-SR?
Other than Schedule A (Form 1040) or Schedule B (Form 1040), did you attach any federal forms or schedules to your federal Form 1040 or 1040-SR?
If No, do not attach a copy of your federal Form 1040 or 1040-SR return to Form 540.
If Yes, attach a copy of your federal Form 1040 or 1040-SR return and all supporting federal forms and schedules to Form 540.
Scroll way down to filing your return
https://www.ftb.ca.gov/forms/2023/2023-540-booklet.html#Instructions-for-Form-540
