All new Samsung mid-rangers are also having 6 inch plus size screens. Please check their website to find the same.
Large screens have been the trend due to OTT services streaming. Earlier 5.8 inch Samsung Note was considered as 'large screen device'.
Samsung also tested Samsung Mega series few years back but people didn't gave it much response. Now those sized screens are selling well.
P.S. Typed this from a 6.4 incher Samsung device.