In QuickBooks Online, the option to add tags in time entries is unavailable. You can only add projects to your time sheets. However, you can consider adding a note to your entries to indicate that it's for a job. Follow these steps on how to add a note.
Here's how:
Go to Time. Then, select Time entries.
Click Add time, then locate the Note section.
Please add a description to facilitate easy identification in the report.
Hit Save.
I can also provide the steps for running the report for your time entries in QBO.
Here's how:
Go to Reports. Search for Recent/Edited Time Activities Report on the search bar.
Locate the employee that you added a note for a job in the time sheet.
Look for the note you've entered in the Memo/Description column.