don't know indenting of break and continue

[perfringo]

It is unclear what should happen with Justin Bieber (should he be excluded from printing out) and should enumeration be continous or not (in example there are 1, 2, 4, 5)

Following approach assumes that Justin Bieber must be included and only message should be displayed.

Start with defining what should happen in spoken language:

Output:
repeat 7 times:
    if something is anwered:
         if answer is justin bieber then express disdain
    store answer somewhere

    else (no answer):
        print message that there is less than 7
        break

You can get to else branch only if there are less than 7 answers (if there are 7 answers for-loop will stop itself with no possibility to end in else branch).

In 3.8 <= Python it could look like:

artists = list()

for i in range(7):                                      # repeat seven times
    if (artist := input('Enter Musical Artist: ')):     # if there is an answer (truthy, i.e. not empty)
        if artist.lower() == 'justin bieber':           # if the answer is justin bieber
            print('No way!')        
        artists.append(artist)                          # append artist to list (even Justin Bieber) 
    else:                                               # nothing entered
        print("That's less than seven but it's ok.")
        break


print(*(f'{num}. {artist}' for num, artist in enumerate(artists, start=1)), sep='\n')