Cmake link own library with multiple other libraries

I have a project and the file structure of it looks like this:

|-- CMakeLists.txt
|-- build
|-- include
|-- libs
|   |-- glad
|   |   |-- include
|   |   |   `-- glad
|   |   |       `-- glad.h
|   |   `-- src
|   |       `-- glad.c
|   `-- glfw
|       `-- include
|           `-- GLFW
|               `-- glfw3.h
|-- sandbox
|   |-- CMakeLists.txt
|   |-- build
|   `-- main.cpp
`-- src

and i want to link the project as a static library. the goal is, that at the end i can just say, in the CMakeLists.txt file of sandbox:

target_link_libraries(sandbox <path_to_library>/libsomething.a)

and with that, i also want glad and glfw to link/compile. my current CMakeLists.txt file of the root folder looks like this:

cmake_minimum_required(VERSION 3.10)
set(CMAKE_CXX_STANDARD 17)
set(CMAKE_CXX_STANDARD_REQUIRED ON)

project(luna)

find_package(glfw3 3.3 REQUIRED)

file(GLOB_RECURSE SRC_FILES src/*.cpp)
add_library(luna ${SRC_FILES} libs/glad/src/glad.c)

target_link_libraries(luna glfw)

target_include_directories(luna PUBLIC include libs/glad/include libs/glfw/include)

and the CMakeLists.txt in sandbox like this:

cmake_minimum_required(VERSION 3.10)
set(CMAKE_CXX_STANDARD 17)
set(CMAKE_CXX_STANDARD_REQUIRED ON)

project(sandbox)

find_package(glfw3 3.3 REQUIRED)

add_executable(sandbox main.cpp)

target_link_libraries(sandbox <absolut_path_to_library>)   

im not expecting that the file structure is perfect at the moment, so tips on improving it would be very welcome.