I would imagine that executable size increases, meaning it has to be aggressively optimized for cache locality?
I would imagine that some types of softwares are better suited for either CISC or RISC, like games, webservers?
Most of the time, nothing; code correctly written on higher-level languages like C should work the same. The biggest difference, the weaker memory model, is something you also have on most non-x86 architectures like ARM (and your code shouldn't be depending on having a strong memory model in the first place).
> I would imagine that executable size increases, meaning it has to be aggressively optimized for cache locality?
For historical reasons, executable code density on x86 is not that good, so the executable size won't increase as much as you'd expect; both RISC-V with its compressed instructions extension and 32-bit ARM with its Thumb extensions are fairly compact (there was an early RISC-V paper which did that code size comparison, if you want to find out more).
> I would imagine that some types of softwares are better suited for either CISC or RISC, like games, webservers?
What matters most is not CISC vs RISC, but the presence and quality of things like vector instructions and cryptography extensions. Some kinds of software like video encoding and decoding heavily depend on vector instructions to have good performance, and things like full disk encryption or hashing can be helped by specialized instructions to accelerate specific algorithms like AES and SHA256.