Is there any way or software to create realistic terrain? 

Yes, you can use real photos and to make the sky dome or sky match you can use programs like Adobe Photoshop to make the sky in those photos transparent. You can also use videos for the backgrounds. Most of it is limited to your imagination. A lot of photo based textures and videos will require a powerful computer to shorten render times or possible crashes. The guys in the marketplace have done a good job and has a variety of scenes and terrains. I don't think they have a static terrain editor.    

Home built; ASRock X570 Pro 4, AMD Ryzen 9-5950X CPU, AMD RADEON RX6900XT, 16GB video card, 131GB of RAM.

What sort of terrain do you need?

Relatively flat?
Small (a few city blocks) or sprawling (a drive on a country road)?
Deep, sharp canyons?
Mountains?

I did make a simple "height map" terrain once.  There are various tools available, depending on your needs.  In my case, I quickly realized it was not a task that held much interest for me (so many other things I'd rather do), which is why I only used a rudimentary approach.

Clarifying your goal might help you get more specific insight from people who have more experience in those areas.

Maybe you will soon become our terrain expert.  Who knows?

Good luck, and have fun.

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iClone 7... Character Creator... Substance Designer/Painter... Blender... Audacity...
Desktop (homebuilt) - Windows 10, Ryzen 9 3900x CPU, GTX 1080 GPU (8GB), 32GB RAM, Asus X570 Pro motherboard, 2TB SSD, terabytes of disk space, dual  monitors.
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It is worth having a look at the built-in heightmap terrain as well. Not only does it allow importing grayscale heightmaps, but also supports 4 material splat maps.

This video tutorial is a good introduction.

Yes agree with JustAViking. To get the best help possible you need to clarify your goal more fully
How to do it depends greatly on what you are doing.
For example, I think photos can produce good realistic terrains for use in videos but are not very effective for game creation unless they are way in the background where the player never goes.
One issue with photos for terrains etc in films, I think, is having the camera moving makes it look like a photo instead of 3D.
So I have tried a few experiments to see how photos might be made to look 3 dimensional within camera motion.
Here are 3 of my attempts (from quite some time ago) and I find it works for me but it all depends on peoples preferences I think
Here I got a photo, cut all the parts of it up, updated those cutup images to complete them (too a degree, its just experimenting) and then put those images onto faces and scaled/positioned them to make the scene. Then I added 3D characters, 1 3D car and animated it to see how it would look. Needs more work but not too bad I think


This next one I tried I tried using basically shaped 3D faces instead of flat ones like in the first experiment. Again more work is needed.
One big issue with it that needs more work/experiments is the shadows in the photo.


Finally, this one is just a single photo on a single face.
I added a few waterfall particle effects to make the water look like its flowing and I added a few trees and made them look like they are flowing with the wind


I don't know if these experiments will be helpful to you?
Just showing some options I have tried and didn't mind how it looked.






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@Rampa - Thanks for for linking to that tutorial.  That is the method I used for the terrain I created.  I think it provides a reasonable balance between ease-of-use with quality results.

@Delerna - Good examples.  I especially like the first one, including the rotation at the end that reveals the magic.  Thanks.

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iClone 7... Character Creator... Substance Designer/Painter... Blender... Audacity...
Desktop (homebuilt) - Windows 10, Ryzen 9 3900x CPU, GTX 1080 GPU (8GB), 32GB RAM, Asus X570 Pro motherboard, 2TB SSD, terabytes of disk space, dual  monitors.
Laptop - Windows 10, MSI GS63VR STEALTH-252, 16GB RAM, GTX 1060 (6GB), 256GB SSD and 1TB HDD