What tuning does Julia Jacklin use on "Pool Party" and how does it affect her vocal delivery?

She plays it in an open D tuning (D A D F# A D). The low D drone gives the guitar a rumbling, hypnotic foundation that sits low in the register, pushing her voice up and out. She’s not fighting to be heard over the guitar; she’s soaring above it, making her vocal feel fragile and exposed but also powerful.