I would visit the orange pippin website. They have detailed descriptions of the apples and tree habits for a bunch of apple trees. I have added the link for the Duchess of Oldenburg below. There are several tabs for each apple. The “fruit id” tab has information about fruit description, tree habit, and fruit uses. The “review” tab has reviews from different people who grow and eat the apple-for example Duchess of Oldenburg has 4 reviews and each review also gives the location of the reviewer. Locations are helpful since how apples do and taste is often location dependent. Hopefully, this helps.
Apple - Duchess of Oldenburg - tasting notes, identification, reviews
-mroot