There's dated and there are trends that are dated.
If you buy a house that hasn't been decorated for decades, it will likely be dated. It may have swirly carpets, old fashioned wallpaper, 1970s furniture. All of those things will not look dated in an otherwise up to date bang on trend house (House of Hackney maximalist style).
Then there are trends that are dated because they were trends from 2021, or 2020. Trends cycle super quickly. So for example, grey kitchens are out of trend. Dark blue kitchens are out of trend. We are now seeing on trend green and some pink kitchens. Another super on trend item which will be dated in a couple of years is Crittal doors.
If you want a continually trendy home, then one way to do it so to paint the walls soft white (yes white!), buy classical designer type furniture and then accessorise with super trendy (throwaway) pieces, like cushions.
Whatever you do, don't decorate like Insta influencers who style a bathroom with a plant in front of the WC and a pile of towels on top. It's styled for a photo, not to live in!