How can I make this image bigger and not lose resolution?

[Jua Anto]

This illustration is from a pc game. The game is called Gachinko Bitch Club. I asked the company that distributes it, but they told me that this is the only image they have without text. How can I make this image bigger, and make it gain in resolution too? do you recommend any free program if possible for this? Thank you very much.

 

[Leggy]

I routinely resize my images with this simple, free app, Resizer For Windows.

https://download.cnet.com/Image-Resizer-for-Windows/3000-12511_4-75937402.html

Download and install.

Highlight the pic(s) on your computer. Then right click. Select Resize Pictures. Choose the desired size, and click Resize (or Enter).

Works fine for me, on Win 10. Think you'll like it.

Hope this helps. :)