In Switzerland, VAT is required from an annual turnover of CHF 100,000 (Art. 10 VAT Act). This applies to any employment, including sex work, OnlyFans and cam income. Sex work is not exempt from VAT (unlike medical services).
VAT rate on sex work: 8.1% (standard rate). If VAT is required: monthly or quarterly billing with the Federal Tax Administration (ESTV), input tax deduction on business expenses possible.
Anyone who is likely to exceed the threshold should involve a trustee - subsequent billing is complex and expensive.