@Kirtan_Bhad
Unfortunately, this is currently a known limitation of the built-in TTS node.
As a workaround, you can use the Podcast Generator plugin, which supports the Instructions feature (I added this feature for this purpose 
). Although this plugin is designed to generate conversation-style voices for two people, you can generate a single voice by passing in a one-line script and filling the Voice 2 parameters with dummy data.
Of course, you can also use the HTTP node to call the OpenAI API directly.
Hope this helps.