I think there probably is a plan but it's sketchy, politically very highly charged, and will contradict not only Treasury orthodoxy but mainstream economic expertise. There's little upside in announcing stuff like that, especially now, having thrown a couple of hand grenades into the media/markets already: few people are going to be reassured.
My sketchy sense of what "the plan" might be for growth is based almost entirely on this Spectator article, which I've linked to before: despite the publication and the author it really is very helpful:
https://www.spectator.co.uk/article/trussonomics-a-beginners-guide
I'd say the plan involves, broadly, conventional supply side tax cuts to get everybody working hard; increased interest rates to encourage productivity; greater openness to the use of fiscal policy, including industrial strategies, and of course deregulation - specifically in data, biotech, care - and housebuilding. Oh, and NHS privatisation!
Now, some of that looks economically illiterate to me, from the little I know (deregulating childcare is not going to make it more productive), and politically difficult relative to the potential gains (data, NHS). The one exception as far as I can see is housebuilding. If they can actually get a programme of housebuilding going, at the same time as bringing prices down through increased interest rates, then that is potentially a very politically popular thing, and it seems reasonable to believe it could boost the economy in various ways, direct and indirect.