My experiences of houses in the 80s/ original 80s design:
Traditional 3 bed semi, small kitchen (possibly slightly extended), had a pull down table for breakfast/ lunch/ tea. Dining room off hallway for whole family dining.
Traditional 3 bed semi, very small kitchen. Dining room (front) knocked down into lounge. Accessed off hallway.
Large Edwardian house, good size kitchen still with 60s (possibly 70s) fitted units, larder. Opened onto "breakfast room" Had seperate formal dining room for special occasions (plus lounge)
Large pre-Victorian house, "breakfast room" knocked through to kitchen. Beige fitted units with wood trim. Seperate formal dining room, lounge and "living room"
80s house 3 bed. Seperate rooms with serving hatch. Beige fitted units with wood trim. Had utility room off kitchen.
80s house 4 bed. Originally seperate rooms with doorway joining. Had utility room off kitchen.
80s DIY was often not kept up to date and following trends. There was a lot of mid-century decor surviving that was built to last and used to death.
80s could be an odd mix of modern beige units, but dining rooms had throw backs to dark, hardwood pre-dating minimalist light wood of the post-war mid-century style. Mahogony was desirable before it was banned due to deforestation. Decor could be quite chintzy (heavy florals) or plain magnolia. Collectibles or "best china" were desirable and might be displayed on a dresser. Decor was unlikely to be very matchy and could be a bit jumbled by current standards.
A newer house would retain the building specs it was built with. Owners were unlikely to rush into changing for fashion and to personalise.
An older house could retain older decor and often have a collection of different periods going on. Restoring older features covered up/ removed in mid-century trends wasn't a high priority, nor decorating in sympathy to the house's original era.