Edits to multiple entries can be executed using the Multi-Select tool on iOS.
Tap the More (•••) button at the top right and then Select Entries, or swipe on an entry and tap the Checkmark icon to activate Multi-Select.
Once multi-select is enabled, tap the button to the left of each entry to include in the bulk actions. At the bottom there are options to Move to a different journal, Tag, Add/edit location, Delete, Share, and Merge selected entries.
You can also tap Select All to select all entries in the specific view, or View to view all selected entries at once.