Bash Sed Utility Help

i got a string with multilines in a text file my_file.txt, ex below:

plmn_list: [
 "2020",
]

i need to replace the string. i used bash sed method to make so but it fail,
sed -i 's/plmn_list: \s*[[^\]]*\]/new_text/g' my_file.txt,
any help would be great. :sweat_smile: