Locking down the phone without replacing what she's getting from TikTok won't stick. You'll just create a cat-and-mouse game where she finds workarounds and resents you more. The real issue is that those apps deliver constant dopamine hits - social validation, novelty, zero friction - and you can't compete with that by saying "go read a book" or "do your homework."
Here's what actually moves the needle: find something that gives her the *same* psychological payoff but requires her hands and brain simultaneously. This could be anything - photography, making short videos for something she cares about, pottery, skateboarding, rock climbing, even building PCs or gaming competitively. The key is it has to feel self-directed, not like punishment. Guys, notice that the garden example works because it's tactile, shows visible progress, and doesn't feel like parental force-feeding. You need that same vibe. Sit down with her and ask what she *actually* cares about rather than telling her what to do. Yeah, it takes effort, but you're basically offering her a better deal than TikTok, not just yanking it away.
One pitfall nobody mentioned: if you do manage to get her off the app, don't immediately try to fill every hour with structured activities or academics. That's how she ends up right back on TikTok the moment you're not looking. Give her some unstructured boredom too - that's actually when real interests develop. The confiscation plus boredom combo is what makes kids most desperate to scroll. Also, if there's anxiety or depression underneath this (avoidance behavior), that's a separate issue worth exploring with someone qualified.