Yes and no.
Yes - All the training plans are scaled to each persons level of fitness. My wife (and my mother) use TR for exactly the case you are laying out for your wife. My wife in fact has no interest in riding her bike outdoors at all, let along race. But we have a setup in the garage that makes it easy for her to do workouts without much fuss. It doesn’t matter that her FTP is less than 1/3 of mine, she gets a good workout, is getting fitter and feels good. Weight loss is just math; calories in vs calories out. Exercise in any form will help with the calories out part of the equation, but you can lose weight without any exercise at all. Is high intensity interval training effective at torching calories though? You bet.
No - I’d say a lot of TR users don’t race, however most are trying to be fitter/faster on their bike. So, the focus on structured interval training is designed to condition your body to be a more efficient/stronger cyclist. Therefore, there aren’t any training plans designed specifically for “weight loss”. They all will do that, but it’s not the focus of the platform. I think what you’ll find is that the intervals make indoor workouts more interesting however and as I said, is scaled to the level of fitness of the specific user so nothing is out of reach.
I’d say give it a try. Good plans to get rolling with are Sweet Spot Base 1 (low volume), followed by Sweet Spot Base 2 (low volume) and then Sustained Power Build (low volume). I’d skip Speciality and just go back to the beginning again. If you want a trial license for your wife to try it, PM me and I’ll hook you up.