Cannot change font size of text field in material ui

I am trying to learn material ui. I want to enlarge the text field on my page. However, the styles i embed with the field changes height, width and other properties except the size. Following is my code:

const styles = {
container: {
    display: 'flex',
    flexWrap: 'wrap',
},
textField: {
    // marginLeft: theme.spacing.unit,
    // marginRight: theme.spacing.unit,
    width: 300,
    margin: 100,
    fontSize: 50 //??? Doesnt work
}
}

Following is the stateless component(React):

const Searchbox = (props) => {

    const { classes } = props;

    return (
        <TextField
            onKeyDown={props.onKeyDown}
            id="with-placeholder"
            label="Add id"
            placeholder="id"
            className={classes.textField}
            margin="normal"
            autoFocus={true}
            helperText={"Add an existing id or select "}
        />
    );
};

export default withStyles(styles)(Searchbox);

I totally understand there is no rocket science as its a straightforward CSS in JS approach of applying styles.

However, I cannot override the base font size for my text field. Any help will be appreciated

As mentioned in the page TextField API apply styles to the InputProps which applies style to the input element.

Here is the code:

const styles = {
  container: {
    display: 'flex',
    flexWrap: 'wrap',
  },
  textField: {
    width: 300,
    margin: 100,
  },
  //style for font size
  resize:{
    fontSize:50
  },
}

<TextField
  id="with-placeholder"
  label="Add id"
  placeholder="id"
  InputProps={{
    classes: {
      input: classes.resize,
    },
  }}
  className={classes.textField}
  margin="normal"
  autoFocus={true}
  helperText={"Add an existing id or select "} />