Look, maybe... but probably not. The issue is a lot of non-athletic, non-healthy people think "a lot of exercise" is a brief walk in the park, and "a healthy diet" is about 2500 cals of snacks and wine.
If you were to genuinely commit to 600-800 calories of exercise, and eat 2000 cals a day, you'd be on 1300-1400 and you'd lose weight. You could do 500 cals of exercise and eat 2000, totalling 1500 a day.
But people just don't. They burn 200 cals on a brief walk and eat 3000.
OK, you're doing 45mins of spin a day. That's fair. Wear a heart-rate tracker and see how much that's burning.
Then, what do you eat? A "normal" bowl of porridge could be 700 cals if you make too much. A "normal" sandwich could be 600 if it's overloaded with cheese and mayo. Your "normal" dinner could be 500 cals of rice alone.
So, you really will need to keep an eye on the food and weigh it, so you're not undoing all your hard work daily. I do a lot of strength training, started competing before Covid, more than happy with my figure and keen to keep food in balance so I can gain or lose as I want to, and I still keep an eye on the food and calorie intake. It's very easy to binge away benefits.
(ffs people stop telling her she'll 'be building muscle' on a bloody spin bike. You build muscle with a calorific surplus, which she is trying not to eat, and she's not taxing the muscle with resistance. She'd have to strength train to build muscle. Give over with the fairy tale that 'the scales just show you're gaining muscle' when all the scale shows is how many biscuits you've been having.)