Hi KRU1,
Please use below link to check your California state tax year 2020 refund status:
https://www.ftb.ca.gov/refund/index.asp
Regarding stimulus payments, below IRS links explains how to receive the 3rd stimulus check, and how to claim Recovery Rebate Credit for 1st and 2nd stimulus checks (if not received) on your 2020 tax return.
https://www.irs.gov/coronavirus/economic-impact-payments
Hope this helps. Thank you.