Generally the main tag must be one and unique to the entire Web Application or the Custom HTML Page. Technically it it okay to use the main tag inside the div tag but it not the correct way of maintaining the semantic passion in the code. in the React or Next JS Application it is better to wrap the root entry point with main and then we can use the other semantic tag like section , header, nav, figure inside the App. Even inside the div also we can use the other semantic tags excepts main.