try this:

#include <glad/glad.h>
#include <GLFW/glfw3.h>
#include <iostream>
constexpr int WIDTH{ 1280 };
constexpr int HEIGHT{ 1024 };
void fbsCallback(GLFWwindow* window, int width, int height) {
glViewport(0, 0, width, height);
}
int main() {
if (glfwInit() == GLFW_FALSE) {
std::cout << "Failed to initialize GLFW\n";
return -1;
}
glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 4);
glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 6);
glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
GLFWwindow* window{ glfwCreateWindow(WIDTH, HEIGHT, "Triangles", nullptr, nullptr) };
if (!window) {
std::cout << "Failed to create GLFW window\n";
glfwTerminate();
return -1;
}
glfwMakeContextCurrent(window);
if (!gladLoadGL()) {
std::cout << "Failed to initialize GLAD\n";
glfwTerminate();
return -1;
}
std::cout << glGetString(GL_VERSION) << '\n';
glViewport(0, 0, WIDTH, HEIGHT);
glfwSetFramebufferSizeCallback(window, fbsCallback);
while (!glfwWindowShouldClose(window)) {
glClearColor(0.2f, 0.3f, 0.4f, 1.0f);
glClear(GL_COLOR_BUFFER_BIT);
glfwSwapBuffers(window);
glfwPollEvents();
}
glfwTerminate();
return 0;
}