Love it or hate it the standard Calendar app does the job for me, it’s basic but has enough view options for me to see what’s going on in my day. With iPadOS 13 there aren’t a lot of changes but some little UI tweaks I’ve discovered that make things a little simpler.
If you have a lot of all day events you used to have to scroll in the little windows in the top, now it shows all of the events, a radar I raised and glad to see it’s implemented.
When viewing your calendar in week view you can pinch to compress the items to see it in a smaller view. Basically it seems to compress any free time to show the calendar events closer together.
I’ll update this post as I discover more.