Images for theme import

Hello, I saw in some themes that they use black and white images when importing demos.
Can I make the main images of the demo only black and white? Or should I use other images?
And another question, is there a tool or site to get wireframe images?

Placeholders are the best option for the review process

There’s several tools out there to create these, just Google it

I did not understand correctly!
Search for “Placeholders” ?

You can use any images for the demo (assuming you have the license to add them to a commercial project) but in the download of the item you need to take the demo images out and replace them with placeholder images

Great, I found the answer
I will send an item, please tell me, is this acceptable?

Maybe but it would still be better and less of a risk to use proper placeholders