Most adult kids default to a card plus a small gift for Father's Day. The default is fine but it is also the same gift he has been getting for forty years. The upgrade move is one specific gift he would not buy himself, paired with the card.
Set the quiz to 'My dad' for the relationship and 'Something pampering' or 'Something useful he will reach for daily' for the indulgence question. The quiz weights consumables and small luxuries higher than experiences (which require coordination) and large keepsakes (which he may not have space for).
Strong picks for grown kids. Whiskey tasting flight set ($60 to $180). Pour-over coffee starter kit ($90 to $220). Single-origin chocolate flight ($28 to $65). Skincare set for men ($60 to $160). Merino wool sock six-pack ($60 to $140). Engraved leather wallet ($80 to $220).
How to ask without giving it away. Three weeks before, in passing: 'What is something nice you have been thinking about lately?' Most dads answer this honestly because it does not feel like an obligation. Write down the answer immediately.
The pairing rule for adult kids. One thoughtful physical gift plus a handwritten card naming three specific things you appreciate about him, ideally with concrete moments. Generic 'thanks for everything' is the construction-paper card energy you are trying to graduate from.
What to skip. Generic 'best dad ever' anything. Bundle gifts from chain retailers. Gifts that come with assembly required, account setup required, or a return-if-it-does-not-fit step. The bar at this stage is: he should not have to manage the gift.