Hi @George32 and welcome to the forum,
It depends what part of the project overview you’re referring to.
You can populate the initial “Project description” using this Asana API element:
https://developers.asana.com/reference/project-briefs
You can populate project-level custom fields using the custom fields API element:
In both cases, I’m almost positive Zapier doesn’t provide built-in support for those elements so you’d need to use the “Webhooks by Zapier” feature which lets you do any standard web API call from Zapier to another app: