Combined 2 solutions to achieve purpose of scrolling with custom font on Android and long text not render on iOS: - https://github.com/facebook/react-native/issues/18132#issuecomment-499267942 - https://github.com/facebook/react-native/issues/19453#issuecomment-481071561

ScrollWithCustomFontFixedTextInput.js

import PropTypes from 'prop-types';
import React, { useCallback, useState } from 'react';
import { TextInput } from 'react-native';

/* 
  Combined 2 solutions to achieve purpose of scrolling with custom font on Android and long text not render on iOS:
  - https://github.com/facebook/react-native/issues/18132#issuecomment-499267942
  - https://github.com/facebook/react-native/issues/19453#issuecomment-481071561
*/
const ScrollWithCustomFontFixedTextInput = props => {
  const {
    style,
    children,
    onContentSizeChange,
    multiline,
    editable,
    initialHeight,
    width,
    ...other
  } = props;
  if (onContentSizeChange || multiline || editable) {
    console.warn(
      'onContentSizeChanged, multiline and editable props are not supposed to be changed in this component',
    );
  }

  const [textInputHeight, setTextInputHeight] = useState(initialHeight);

  const onContentSizeChangeFix = useCallback(
    event => setTextInputHeight(event.nativeEvent.contentSize.height),
    [],
  );

  return (
    <TextInput
      style={[
        style,
        {
          height: textInputHeight,
          minHeight: initialHeight,
          width,
        },
      ]}
      onContentSizeChange={onContentSizeChangeFix}
      multiline
      editable={false}
      {...other}>
      {children}
    </TextInput>
  );
};

ScrollWithCustomFontFixedTextInput.propTypes = {
  ...TextInput.prototype.props,
  initialHeight: PropTypes.number.isRequired,
  width: PropTypes.number.isRequired,
};

export default ScrollWithCustomFontFixedTextInput;

Use it like this

<ScrollWithCustomFontFixedTextInput
            style={[styles.introText, { marginBottom: 40 }]}
            initialHeight={Dimensions.get('window').height}
            width={Dimensions.get('window').width - 20 * 2}>
       some text
</ScrollWithCustomFontFixedTextInput>