<Dialog>
fullWidth={true}
maxWidth={'lg'} ------- 'sm' 'md' 'lg' 'xl'
</Dialog>
import { makeStyles } from '@material-ui/core/styles';
const useStyles = makeStyles(theme => ({
dialogPaper: {
height : '400px'
},
}));
//then in your dialog
<Dialog classes={{ paper : classes.dialogPaper}} >
//...
</Dialog>