You should use JSX instead of string:

<div>No results.<br />Please try another search term.</div>

Because each jsx should have 1 wrapper I added a <div> wrapper for the string.

Here it is in your code:

render() {
   let data = this.props.data;
   let isLoading = this.props.isLoading;
   let isDataEmpty = Object.entries(data).length === 0;
   let movieList = isLoading ? <Loader /> : isDataEmpty ? <div>No results.<br />Please try another search term.</div> :
       Object.entries(data).map((movie, index) => <MovieTile key={index} {...movie[1]} />);
   return (
       <div className= movieList >{movieList}</div>
   );
}

You can use CSS white-space to solve the problem.

React Component

render() {
   message = `No results. 
 Please try another search term.`;
   return (
       <div className= new-line >{message}</div>
   );
}

CSS

.new-line {
  white-space: pre-line;
}

OUTPUT

No results.
Please try another search term.

break text to line:

render() {
  ...
  <div>
    {this.props.data.split( 
 ).map( (it, i) => <div key={ x +i}>{it}</div> )}
  </div>
  ...

Some HTML elements such as <img> and <input> use only one tag. Such tags that belong to a single-tag element aren t an opening tag nor a closing tag. Those are self-closing tags.

In JSX, one has to include the slash. So, remove <br> and try <br />

Here is how I got around this. Let message be the prop/variable that has the string containing line breaks to be displayed in HTML as follows:

message =  No results.<br>Please try another search term. ;
<div>
  {message}
</div>

To make this work, we need to use instead of break tag <br> and set the following css on the wrapper element of this message as follows:

message =  No results.
Please try another search term. ;
<div className="msg-wrapper">
  {message}
</div>

CSS:

.msg-wrapper {
  white-space: pre-wrap;
}

OUTPUT:

No results.
Please try another search term.

If you don t want put the string inside a <div> you could use <> to do it.

Like this:

var text = <>This is a text in the first line;<br />this is a text in a second line</>;

Just split text by /n, I do this in this way:

<div>
    {text.split( 
 ).map((item, i) => <p key={i}>{item}</p>)}
</div>

Try with span

return (
           <div className= movieList ><span>{movieList}</span></div>
       );

If you are like in my situation and you don t want to add css, you can do that :

render () {
...
return (
...
<Typography component="p">
...
{(contact.lastname)?<div>Hello {contact.firstname} {contact.lastname}</div>:  }
...
</Typography>
...
);
}

using `
worked for me however i am not sure if it is the exact solution to the problem :

 import React from  react ;
import ReactDOM from  react-dom ;

let element = (
<div>
  <h1> Hello world</h1>
  This is just a sentence <br></br>
  But This line  should not be in the same previous line. <br></br>
  The above content proves its working. <br></br>
  npm v6.14.6 | react : {React.version} 
</div>
);

ReactDOM.render(element,document.getElementById("html-element-id"))

You can add a span tag and add block as a class.

Pomodoro Technique Timer <span className="block">with Bla</span>

The simplest thing which I did is by creating a component.

const EmptySpace = ({ spaceCount = 0 }) => {
  return (
    <>
      {Array.from({ length: spaceCount }, (item, index) => {
        return <br key={index} />;
      })}
    </>
  );
};

export default EmptySpace;

<EmptySpace spaceCount={1} />

In your case you could do something like this:

const msg = (
    <p>
      No results <EmptySpace spaceCount={2} />
      Please try another search term.
    </p>
  );

can pass the content as an array ref: https://reactjs.org/docs/jsx-in-depth.html

Page

import MyComponent from  ./components/myComponent ;

export default function Page() {
  return(
        <div>
            <MyComponent
              content= {["Line 1", <br/>,  "Line 2", <br/>, "Line 3"]}
            />
        </div>
  )
}

React Component

export default function MyComponent(props) {
  return (
    <p>
        {props.content}
    </p>
  )
}

OUTPUT

Line 1
Line 2
Line 3