Do apps just update pre-planned at midnight or does someone actually have to manually push a button?

For example let‘s say a company like Walmart or H&M has an app and at midnight every day that app changes its offers, its deals and products the company wants to highlight when you open the app.

But sometimes also prices change at midnight or restocks happen at midnight. So my question is if the company can pre-plan these exact changes and the app makes those changes by itself at midnight or if some poor employee actually has to manually push a „go live“ or „update“ button at midnight.

I‘m so sorry for this question but its past midnight where I live, I‘m extremely sleep deprived and I don‘t think I can actually fall asleep until I know the answer.