I found this guide helpful: https://medium.com/snowflake/snowflake-security-service-accounts-9663beeb1d30 Just replace the text for the RSA_PUBLIC_KEY with the actual public key that you generate.

-- Create Service User
CREATE OR REPLACE USER ingestionservice 
    DEFAULT_ROLE = 'INGESTION_ROLE' 
    TYPE = SERVICE DEFAULT_SECONDARY_ROLES = ('ALL') 
    -- NETWORK_POLICY = INGESTIONSERVICENETWORKPOLICY -- Recommended: see the link for details.
    RSA_PUBLIC_KEY='MIIB....' -- Snowflake shows how to create this here: https://docs.snowflake.com/en/user-guide/key-pair-auth
    COMMENT = 'Service User for Ingestion';