I want to edit multiple items (using a smartphone)

❓Help
#1

I am using Android 12.
I want to edit multiple items in one document, is that possible?

For example, I want to do something like the following.
・Select multiple items and then delete or duplicate them.
・Select multiple items and gather them in new parent item.（like this image in below）

☆A
☆B
☆C

⇩
★ALPHABET( new parent item）
──☆A(child）
──☆B(child）
──☆C(child）

If you know any useful shortcuts, please let me know. (I’m writing from Japan, so I’m sorry if the grammar is wrong!)

#2

In the top bar (don’t have a screenshot right now), hit the icon with a box and a checkmark in it. It will activate multiple selection mode. Then tap all the items you want to do stuff with (they will get highlighted). Now in the toolbar do whatever you need and tap the box icon again to unactivate multiple selection mode