Depends on the loan. In general, you can modify whatever you want with a car under loan but NOT under lease. However, modifications usually mean your car is worth less and you have a higher chance of being underwater, so could result in an additional financial liability in the case of a repo.

She makes anywhere between $18k - $30k per month from patreon alone, on top of her youtube revenue. I think she's well past being burdened by such issues.

I would imagine a youtuber of her caliber would expense this as a business purchase. I doubt she took a loan for this.