If you are a W-2 employee and all your work is actually (physically) performed in your state of residency and you never physically work in CA, then you would have NO "CA sourced income". This is true even if you work for a California based employer.
In California that rule does not apply to the self employed. Due to a 2019 court ruling in CA, if you are a sole proprietor and you provide services to a client located in CA, that income is taxable by CA - even if you never set foot in California.
