Oversized is not the same as too big. The first is a proportion decision, the second is a sizing mistake, and from a distance they look almost identical. Here is how to stay on the right side of that line.
Balance the volume somewhere
If the top is wide, something else has to be narrow. Oversized hoodie with wide trousers reads as sportswear with no shape at all. The same hoodie over a straight or slightly tapered leg looks deliberate. You are not obliged to wear anything tight, you just need one clean line in the outfit.
Watch where the shoulder falls
A dropped shoulder should land somewhere on the upper arm, not near the elbow. Past that point the sleeve starts to fold at the wrist and the whole piece looks borrowed. This is the single fastest thing to check when you try one on.
Length is what makes it look expensive
The hem should sit at or just below the hip bone. Too short and the volume has nowhere to go. Too long and it starts reading as a dress. If a hoodie is right in the body but wrong in the length, that is worth walking away from, because it is not something you can fix later.
Heavier fabric holds the silhouette
Light fleece collapses on the body, and once it collapses the shape is gone. A heavier loopback or brushed cotton keeps its structure, which is what makes an oversized cut look intentional rather than worn out. It also survives more washes without the cuffs going slack.
How you wash it matters
Cold wash, inside out, and dry flat where possible. Tumble drying is what turns a good hoodie into a shapeless one, usually within a season. If you only change one habit, make it that.