It is very easy to style this black blazer. You can use my combos for all black blazers here
1.The simple and easy way is that you wear the oversized blazer with a white shirt/blouse and the black trousers. You can choose black moccasins, Oxford shoes, and heels to go with this outfit.
2. I suggest you wear the oversized blazer with a gray/ white top and a pair of dark green pants. The top should be a deep v-neck T-shirt.
Wear black shoes with this outfit.
3. You can wear the oversized blazer with the gray top and a black skirt/ black pants. Wear black heels with this combo.
4. You can combine the oversized blazer with black pants/ a black dress and a black top.
Again, you should wear black shoes/ heels with this combo.