In Jainism there isn’t a universal, fixed ritual sequence called a “tap” that prescribes exactly 1 upvas, then 2 upvas, then 3 upvas in all traditions. Fasting (upvas) is a common form of tapas, but how long a fast lasts and when it is undertaken can vary:

• Individuals may observe fasts of 1 day, 2 days, 3 days, or more, often depending on personal devotion, guidance from a guru, or during specific periods like Paryushan/Śravana or during Navpad (nine-day periods in some communities).
• The exact rules and the emphasis can differ between Digambar and Śvetambar communities and among different teachers or monasteries.
• Some practitioners undertake incremental fasting as a personal vrata (discipline), but this is not a single, canonical ladder mandated for all Jains.

If you’d like, tell me which tradition (Digambar or Śvetambar) or which guru or context you have in mind, and I can share more specific details about how fasting is observed in that tradition.