Is there a way to create a new txt file within a process?

Can you explain your use case in more detail?
You can use Text Doc From Template smart service to create a dynamic new text file using the provided template.

Agreed with Sanchit - the Text from Template smart service can be paired with a "blank" template doc (i.e. a text file containing nothing more than one replacement field, i.e. `###textKey###` (etc), to create basically any text file you could possibly want for normal text-file-usage.