unused websites

I have a main site and a new (.design) domain which I got for free. Is there anything productive I can use the fresh domain for, given that the name is in the same niche as my main site. Thanks

Maybe this is easier than I think. A few months ago I read a post on here IDK who but it was really good. They mentioned that they go to old blogs/sites where the people aren't writing anymore and they offer to write for them. I love this idea. However, I am having a problem. Is there anyway...