If she has absolutely no income from anywhere, then no, she would not need to file a US tax return even if she met the substantial presence test.
In order to file an income tax return, she would need to have income.
If she did have income as an employee, and was eligible to file as a US Citizen, she would need to file if she had income of more than $12,950 (standard deduction). Income includes in addition to working, interest, investments, online platforms, selling stuff on eBay and other platforms.