adding new products to the actual niche?

Hi guys,

I have a website with a really good Google ranking that has more than 1k visitors a day.
Up to now, only one type of product is sold in this shop. Can I add other products that have no connection to this topic?
Can I get a better ranking for the new products or is it dangerous and destroys the actual ranking?
Should I get a new domain/website for the new products?

Thank you

please guys i need to know it! many thanks!