Hello, Azure AD B2C SignInSignUp Combined Policy will always display the sign-in form first. You can control settings such as wheter to display the sign-up button or link but not to skip or choose the sign-in first. You may create a custom policy that depending on some custom query params passed (to be read using OAuth2 key-value parameters) can choose to skip the sign-up page and call the sign-in as a sub-journey.
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