そうなるとこれでいいんだ。ありがとう。

cmake_minimum_required(VERSION 3.15)
set(SRC a.cpp b.cpp c.cpp d.cpp e.cpp f.cpp g.cpp h.cpp i.cpp)

add_library(xx_mt ${SRC})
add_library(xx_md ${SRC})
set_property(TARGET xx_mt
PROPERTY MSVC_RUNTIME_LIBRARY
"MultiThreaded$<$<CONFIG:Debug>:Debug>")
set_property(TARGET xx_md
PROPERTY MSVC_RUNTIME_LIBRARY
"MultiThreadedDLL$<$<CONFIG:Debug>:Debug>")
target_include_directories(xx_mt PUBLIC "../include")
target_include_directories(xx_md PUBLIC "../include")