This can get better in future updates, but for arranging and creating columns, I believe Desktop is the way to go.
Also in case it helps, you may missed the following from Notion News:
October 15, 2020
Using Notion on iPad just got a lot easier! If you use an external keyboard, trackpad or mouse with your iPad, you can now:
- Use all the same time-saving keyboard shortcuts from our desktop apps
- Select multiple blocks of content at once
- Click & drag to rearrange content blocks, or selections of multiple content blocks
Coming later: making it possible to select multiple content blocks on mobile without a mouse or trackpad. We're on the case!