Does IRIS products have capability to generate dynamic HL7 message

I would say Yes in the sense that HL7 messages can be constructed entirely from scratch via code.

The main supporting method for this on EnsLib.HL7.Message the method "SetValueAt" can use to add and replace content for an HL7 message.
There are various ImportFrom methods (File, Stream, String) where a vanilla base message can be correlated to an HL7 Message.
The DocType is assigned by method PokeDocType, after which virtual property paths used by "SetValueAt" method will assign content in the right place as expected.
The DTL (Data Transform Language) documents can visually assist converting some other form of structured data into new HL7 messages. They are dynamic in that they can respond not just to a source reference message but leverage Lookup tables to control the content created for output HL7 messages. Then new configuration can be added to lookup tables and this extends the behavior of an existing DTL.

For some code example I have a UnitTest framework class that contains code demonstrating correlation of flat content to an HL7 message, setting the DocType and comparing virtual document paths. https://openexchange.intersystems.com/package/UnitTest-DTL-HL7