I look at it with the rubrik: KISS is for coding. SOLID is for system design. There is overlap obviously but SOLID becomes even more important when you have N+

I look at it with the rubrik: KISS is for coding. SOLID is for system design. There is overlap obviously but SOLID becomes even more important when you have N+2 systems that interoperate. KISS is one way to help ensure you have a SOLIDly designed system when you are coding it. But it helps to understand the principles in SOLID when you are designing a monolith or a set of microservices.