Upgrade to Custom RoM from COS

• Flash SHRP Recovery.
• Navigate to WIPE>ADVANCED WIPE.
• Select System, Cache, Data, Internal Storage & Vendor and wipe.
• Now transfer C20 OZIP to your internal storage.
  (via pc or OTG or SD CARD)
• Navigate to Install, select you OZIP and flash.
• Navigate to WIPE>ADVANCED WIPE.
• Select System, Cache, Data & Internal Storage and wipe.
  (Warning: Don't Wipe Vendor)
• Flash SHRP Recovery.
  (because when you flash OZIP, stock recovery gets installed)
• Mount everything.
• Flash Custom RoM.
• Flash Keystore_Patcher.
• Flash TWRP_Decrypt.
• Navigate to WIPE>ADVANCED WIPE> Select DATA and Wipe
  (repeat 12 & 13, 2-3 times)
• Flash Modified_Boot.
• Flash Magisk 21.4.
• Flash GApps.