One app with more features vs. separate apps focused on one thing

What is considered modern and best for UX with question if to go with one bigger app with more features or separate apps?

I can understand why Facebook split their main app and Messenger, or why Google/Apple has apps for Tasks, Notes, Email, Calendar, Docs, etc, but on the other hand there is Microsoft with Outlook which has integrated more features.

Where is line when to split or bundle apps? For example I have app which has 3 separate services which could be also separate apps easily. But initially I thought that bundling them together would be better for user who could log only to one app, it takes only one space on home screen and can switch between with one tap in navigation.