Andy Galbraith shows how to copy SSIS packages using DTUTIL:
A frequent need when performing a server migration is to copy the SSIS packages from one server to a new server. There are a couple of different ways to do this, including a wizard in SSMS. (See https://www.mssqltips.com/sqlservertip/2061/how-to-manage-ssis-packages-stored-in-multiple-sql-server-database-instances/). The catch to this is that these are manual and they only move one package at a time.I recently had to migrate a server with over twenty packages, and I knew I didn’t want to click-click-click over and over again. 🙂
The best answer would be to have your packages safe and secure in source control, but sometimes that’s not an option.