Then you can resort to polyurethane cornices and moldings (overhead decorative elements, "ceiling plinth".).
They close the junction of two planes, make the transition of walls into the ceiling smooth and soft, small irregularities are hidden.
Only deep matte paints for uneven ceilings.
In such cases, products that create matte finishes work much better. These types of finishes reflect less light, thereby hiding and masking existing irregularities.
Paints with a matte finish are offered by almost all manufacturers of paints and varnishes.
To mask irregularities, paints are used, which are called textural, textured or decorative. The names are different, but the common property is the same: they give a relief surface.
Choose compositions with a matte finish. They do not reflect light and visually smooth out minor defects. Opt for neutral colors.
Walls painted in pastel colors appear smooth and even.
The first method involves the use of dry building mixtures diluted with water, or ready-made solutions.
When performing work in the second way, flat slabs are used, which will then become the surface of the ceiling, for example, drywall.