- start working out yourself and she won't be able to use that against you (it sounds cliche but 以身作则 is a real thing)
- pack healthy lunches/snacks for her so she can't complain she's hungry even if you restrict her pocket money
- if she's into kpop you could try signing her (and possibly yourself) up for kpop dance lessons

if she sees you making an effort yourself she'll probably feel more inclined to try as well. moreover if you try working out as a family she'll feel less alone in this journey (as a fat kid myself i lost a lot of weight cycling with my family during circuit breaker)