This is how a company gets distracted, with too many irons in the fire, and things eventually slide downhill on all fronts. Just sayin'. There is such a thing as simply "too big".
Compared to most other companies a fraction of their size, Apple doesn't make that many products. Physical products that are still in production probably number in the hundreds if you count every different model of Mac, iPhone, iPad and every cable and adaptor they make. Compared to someone like Samsung who make hundreds of different chips, a bunch of memory products, phones (dozens of them), billions of laptop models at one time, SSDs, displays, printers, probably a whole pile more I'm forgetting. LG Philips make phones, displays, light bulbs. Panasonic make everything from DVD players to heavy construction vehicles via industrial air conditioners. Yamaha make pianos and motorcycles. Apples portfolio is tiny given their worth. TikTok would likely just be added to their services division and be given the odd dictations regarding feature sets and APIs. Otherwise leave them to it, they're doing pretty well as-is.
Apple is pretty hands-on - if they buy it, I would expect more of a beats situation. First thing they’d do is mandate new privacy policies, sanitize the back-end infrastructure, etc. Then they’d start building hooks into iOS, to make iphones the best platform for viewing/posting stuff. They’d integrate it into the Apple TV app on Apple TV’s, etc. They’d continue to support other platforms, but I don’t think they’d be “hands off” at all.
Apple is as hands-on as they need to be. Above most other companies acquiring companies, they know the value is in the talent and they don't want to stifle the talent. Other giants buy the company, relocate the staff, reassign them to other groups and make them start working the way their other employees always did. Then they wonder why the lose the magic. Compared to that, Apple is pretty hands-off I think. If it ain't broke....
The only question is whether the kids who love TikTok will accept Apple as their new overlords. That will likely depend on whether Apple manages to succeed in getting older users onto it or not.
I do think they'd keep the Android version though. Just add features sooner/better for Apple devices and make the experience better on those devices as you say.