To create an action creator for fetching data in Redux, use Redux Thunk for async actions.
Example:
const FETCH_DATA_REQUEST = 'FETCH_DATA_REQUEST';
const FETCH_DATA_SUCCESS = 'FETCH_DATA_SUCCESS';
const FETCH_DATA_FAILURE = 'FETCH_DATA_FAILURE';
// Action Creator (Thunk)
const fetchData = () => {
  return async (dispatch) => {
    dispatch({ type: FETCH_DATA_REQUEST });
    try {
      const response = await fetch('/api/data');
      const data = await response.json();
      dispatch({ type: FETCH_DATA_SUCCESS, payload: data });
    } catch (error) {
      dispatch({ type: FETCH_DATA_FAILURE, error });
    }
  };
};