While you plan the upgrade of your Oracle E-Business Suite 12.2 or 12.1.3 environment database(s) to 19c, consider some of architectural changes required including a shift to multi-tenant architecture and database directory objects. Take note of the certified platforms and integrations, along with the certified or supported database features. You can read more in Oracle Database 19c (19.3) Now Certified With EBS 12.1.3 and Oracle Database 19c (19.3) Now Certified With EBS 12.2.
Review the latest support information for Oracle E-Business Suite Release 12.2 and Release 12.1 with Oracle Database 220.127.116.11 or Oracle Database 18.104.22.168 in Extended Support Fee Waiver for Oracle Database 12.1 and 11.2 for Oracle E-Business Suite (MOS Note 2522948.1).
Oracle Advanced Customer Services offers a fixed-fee upgrade service from planning to live. See more information here.