Hailing from the picturesque Australian Blue Mountains, Julia Jacklin settles comfortably into the warm gait and twang of old-time country on her debut album. But while “Pool Party” and “Lead Light” highlight the Patsy Cline-worthy quiver of her voice, “Coming of Age” swerves into fuzzy, jangling rock without surrendering that disarming vulnerability. By the time of the closing title track, which sets Jacklin’s singing to just sparse threads of guitar, her sighing, lived-in delivery has spared no heartstrings whatsoever from its spellbinding pull.