reproduce my electrical circuit

Hi, I’m a beginner and I would like to reproduce my project that detects an electromagnetic field, but on a much smaller electronic board. I want to use a smaller microcontroller and a compact magnetometer to optimize the design and make the PCB as small as possible. I’m not sure where to start. Could someone guide me or point me in the right direction? My goal is to reproduce the project in KiCad, then design a PCB with very small components, maybe using something like a small Arduino board. Any advice or resources would be really appreciated! . I don't know if, when using a KiCad schematic, it is necessary to use special soldered capacitors for a more suitable and specialized circuit. I don't know.