Slow and steady on the weight loss: try using a little scale to weigh the usual portions you give her (you can include the scoop as long as you always use the same one) and after you have an average over a day or two, start making her new portion size just a few grams less. Between that and more playtime she'll slim down without being too mad at you.

If you have only been doing dry food you could also try changing one of her meals to wet food, keeping the same amount by weight. Dry food is more caloric per gram because water is heavy. The extra hydration will help her feel satisfied and be good for her kidneys.

She doesnt need to eat 3x/day tho. It might be a process for both of you to adjust but she's better off 2x/day and up the fun making. Also, what I have found helpful to reduce begging or harassing for food is to have a ringtone that only plays every 12 hrs so she learns yo associate feeding as being preceded by that tone rather than an ad hoc thing she can endless renogotiate you over chronically.

Does she have a cat tower/tree? Those are helpful to keep them active and jumping up and down and shit