This method makes the 3D models (Mario, enemies, coins) look sharp and smooth while keeping original 2D elements. DeSmuME (PC) 3D Settings 3D Rendering Engine OpenGL 3.2 Increase the GPU Scaling Factor (e.g., 3x or 4x). A factor of typically matches 1080p, and achieves 4K. melonDS (PC/Android) Video Settings as the renderer. Adjust the Internal Resolution slider to your preferred HD setting (e.g., 4x or 8x). Method 2: "New-ISH" Super Mario Bros. DS HD (ROM Hack)
Several fan projects have attempted to bridge the gap between low-res sprites and high-res models: New-ISH Super Mario Bros. DS HD new super mario bros ds hd textures
Dedicated modding communities have created specific "HD" packs that replace original assets with higher-quality versions. "New-ISH" Super Mario Bros. DS HD The Evolution of New Super Mario Bros