Nothing different here, like any other living space (house or even professional premises), it is the laying of the Bagua on the plan of the flat that will dictate the colour, the material and the shape to be used in the interior decoration.
Is the kitchen in the northern zone? Then it is the water element that will nourish the area. Is the office in the south-east sector? This is the time to bring in green, brown, green plants to harmonise the energy thanks to the wood element.
For more flexibility, and because the transition from one room to another is more complicated to manage in a flat (and even more so in a studio), the cycle of the 5 Chinese elements will also allow you to bring to the sectors the element that gives birth to it (water for wood, wood for fire, metal for water, etc.).
Finally, decoration in general will have a light hand on the use of decorative objects. The more there is, the more the flat looks cluttered and unbalanced. Harmony also comes from the little, without falling into minimalism.