Yes, as long as the fixed part of the message matches an approved template and your variables sit where the template’s variable parts are.

The safest way:

1. Select the template from the DLT Templates List rather than typing it in. The DLT Template ID is filled in automatically.
2. Put your $CUSTOM1$ style variables in the positions where the template expects variable content.
3. Keep the values in your custom columns within whatever the template permits.

If you type the content manually, you have to enter the DLT Template ID yourself. A mismatch between your content and the approved template fails the messages, so check it on a small batch first.