Sub item in sub item

hi guys, i want to ask for my problem
i have google sheet like this

i want to convert my sheet to
this my progress

how to make sub item in sub item like google sheet???

One option would be in the comment bubble of the bbbb line, you would make a checklist?
Maybe that will help?

thanks for recomended
but when use this. i can’t add time line in sub item at monday workspace