"How about a bag like this?"
こんな is a pre-noun adjective directly modifying the noun かばん - こんなかばん - a bag like this/a bag such as this
こんなに is an adverb that can directly modify verbs and adjectives that act like verbs (such as かわいい)
こんな時計 - "A clock like this" - A similar clock - adjective modifying noun
こんなにかわいい時計 - "A clock as cute as this" - A similarly-cute clock - Adverb modifying adjective modifying noun