Row level security

Hello how would you handle a row level security?

For example I have a projects table that has a ownerId and a second table called members that stores a user/project id How would you make it so only members could update the project?

I'm making a time tracking app so i store the following items:

Projects:

• title
• ownerId
  TimeEntries:
• start/end datetime
• projectId
• userId

I would like so only members could insert a time entry for a certain project

in my old backend code (expressJS) I just made sure that the user was inside of the members table