Do you mean io_uring?
Syscall chaining refers to having the kernel execute consecutive systemcalls without switching the context back to userspace.
An example of this might be closing a multitude of file descriptors or registering signals or writing the same data to multiple fds etc, which becomes prohibitely expensive if you need to do it multiple times quickly, and actually doing it even once is really expensive if your sets are large.
io_uring already gives you that. You can submit multiple operations in a batch and link the operations together so that if one operation in a chain of linked operations fails, io_uring won't try to execute the rest.
io_uring enables exactly this
Chaining RPC calls requires something more sophisticated.
Io_uring is just a way to have "do this and tell me when it's done" io.