I’ve not seen any native way to generate speech from text. If you mean a text to speech plugin, there seems to be one, but I’ve not tried it out. Go into plugins and type texttospeech in the search. This will bring up a text to speech plugin that says it is from Epic. When using a search engine to look it up, this appears to be an experimental plugin by Epic to do something similar to what you are looking for. If the output of a texttospeech plugin is a wave file, then you generate your waves from text, which can then be used in a dialog voice. Edit: I forgot to mention, this is UE5 only.
There appears to be two other plugins, one by google and one by someone else. These are in the marketplace and cost something. Again, if a wave file is generated as output, then you can do something like you are thinking.
Sorry I don’t know more, but that’s a start in looking into this technology.