Modern Elegant Interior Design Conceptualisation

We are looking for an interior designer to develop the interior design and lighting concept for an existing, currently occupied living space consisting of a living room, dining area and kitchen.
This is a renovation and redesign of an existing home, not a completely new interior. The existing architectural layout and several major elements will remain and must be incorporated into the new design. The existing walls, floor tiles and kitchen cabinetry will remain and cannot be replaced. Several existing pieces of furniture and other elements will also be retained.
The goal is to transform and elevate the existing space into a cohesive, modern, elegant and warm interior, while working creatively within these existing constraints.
The living room, dining area and kitchen should be designed as one coherent interior, rather than as three separate spaces.
The project is not intended to be a full architectural or technical construction design. We are primarily looking for well-considered design solutions and practical recommendations.

The designer will be responsible for developing the overall design concept, including the lighting, colours, materials, wall finishes, furniture and accessories. Where appropriate, we would like to receive specific, purchasable products, preferably with alternative options where appropriate.
We will provide a separate document containing the existing floor plan, dimensions, photographs of the current space, and details of the furniture and other elements that need to be retained.
A previously created 3D visualization will also be provided. This should be considered a reference for the desired mood and visual direction only, and not as a final or technically accurate design.
Important
The designer does not need to prepare a complete architectural or construction documentation package. The renovation will be carried out in several stages, and the technical details of the actual installation will be handled by the respective contractors.
What we are looking for is a well-developed and cohesive interior design concept, 3D visualizations, and specific implementation and product recommendations that we can use as a practical basis for renovating and subsequently furnishing the existing space.