I regret to share that TextFrame cannot be used as a separate entity. It is in fact part of any shape and associated with that. Please visit this documentation link to document object model (DOM) of Aspose.Slides and can view the class hierarchies.
I regret to share that unfortunately I don’t have DOM for PPTX available at the moment. However, the DOM for PPT and PPTX is same as far as what you are presently looking for. However, PPTX has added support for charts creation and different mechanism of animation management and includes separate namespace for them. I will request our development team to share the DOM for PPTX as well and will share that in online documentation once it is available.