Create a New Rule, choose the scope (for example, Active Campaigns), the Pause or Activate action and, under Schedule, select Specific Date and fill in the Date and Time. In this mode, you don't need to add any metric conditions: the schedule itself is the trigger, and the action applies to everything in scope at that moment. To limit it to specific campaigns, use Filter by name (for example, Contains: promo). The rule runs once, at the scheduled time (Brasília time, UTC-3), and you get a notification of what was done.

If you only want to set when an ad set or campaign ends (Meta's own end date), you don't need a rule. In Meta Ads, select the items and use End Date in the bulk edit bar.