We don't have a similar local authentication with SAML, like you may have with LDAP integration.
But you can configure Group authentication with SAML, It will create users in Spectrum if not already added manually.
https://techdocs.broadcom.com/us/en/ca-enterprise-software/it-operations-management/spectrum/22-2/administrating/single-sign-on/integrate-with-the-identity-provider-server-from-2126.html#concept.dita_0cf80074-13c4-4eff-b925-8557a2500a23_PrerequisitesSAMLGroupAuthentication