Yes! By default, all your entries will appear in your book unless you decide to exclude some by hand. You can remove individual entries you wish not to include in your books at any time - without deleting the entire entry from the journal.
You can "deselect" entries both in the mobile app or online at app.qeepsake.com.
Selecting entries for the book on the mobile app:
The toggle will turn gray to indicate it won't be included in the book. If the toggle is purple, it means the entry will appear in the book.
Selecting entries for the book online:
The book icon will turn gray to indicate it won't be included in the book. If the book icon is green, it means the entry will appear in the book.
NOTE: In the book preview at app.qeepsake.com/book, all "included" entries will appear in the preview by default for the date range you select.