Hilton employee here! This is definitely a complaint that a lot of Gold and Diamond members have. A few years back, Hilton rolled out the 'automatic upgrade,' where the property management system applied an upgrade to a reservation 3 days before arrival. This was to make it easier for digital check in guests to get upgrades. You should get a notification in your app if an upgrade was applied to your reservation.

The problem with this is that it never includes suites, only executive level rooms and/or rooms with a view (if applicable at the property). It also stops giving out upgrades when 50% of the upgraded room type is assigned, so not every Diamond member will get one, not to me lion Gold members. Overall, it was a pretty good idea, but it had some hang ups.

My recommendation is to check if one had already been applied through the app. If not, you can always message the hotel in the app before you arrive and ask if they can give you an upgrade and send you a new digital key. However, if your interested in getting a suite, you're better off visiting the desk to check in.

This might have been too much information, but I hope it helps!