Yes they need to file their own return for 1099NEC self employment income over $400. So they need to include all their income.
To file a separate return for a dependent you need to set up a new account separate from the parents. Online is only good for one return per account. You can use the same email address for 5 accounts.
Https://ttlc.intuit.com/questions/1894512-how-do-i-start-another-return-in-turbotax-online
Be sure on the dependent return you check the box that says you can be claimed on someone else’s return.
Filing requirements for a dependent
https://ttlc.intuit.com/community/children-dependents/help/do-i-need-to-file-my-own-taxes-if-i-m-a-d...
1099NEC is self employment income. You can enter Self Employment Income into Online Deluxe or Premier but if you have any expenses you will have to upgrade to the Self Employed version. Or use any of the Desktop CD/Download programs.
How to enter income from Self Employment
https://ttlc.intuit.com/community/self-employed/help/how-do-i-report-income-from-self-employment/00/...
