You could theoretically travel outside your 15 minute walk bubble, but it's designed to keep everything you do within the bubble. Work, play, food, shelter.
no it is further than 15 minutes walk away.
I should point out that the urban planning definition of a "15 minute city" is 15 minutes by foot, bike, and public transit. That's quite a bigger bubble than on foot alone, and virtually *all* small towns and minor cities are innately 15-minute. It only becomes a matter of urban planning to preserve that characteristic in larger cities.