ERJ-175 FO reported an upset event after encountering wake turbulence on final approach to LAX in trail of a B787. The flight descended below the glide slope on the approach; likely contributing to the encounter.

Narrative

We were on a base leg for the visual approach; following a heavy aircraft (Boeing 787) we previously reported in sight. ATC cautioned us of wake turbulence when they cleared us for the visual approach. Shortly after we became established on the final approach course; we encountered wake turbulence and the aircraft unexpectedly banked to the left; causing an upset. I called the upset; and the Pilot Flying disconnected the autopilot and recovered the aircraft; eventually bringing the aircraft back to the final approach path. After performing the shutdown checklist on the ground; the Pilot Flying and I debriefed the event.Cause: We backed up the visual approach with the ILS approach. Once we were cleared for the approach; the Pilot Flying armed NAV; set the final approach fix altitude; and armed the approach (we were inside the penultimate fix). The selected vertical mode was FPA (Flight Path Angle); resulting in a gradual descent to the lower altitude selected on the altitude pre-selector. This caused the aircraft to descend below the vertical path; which likely caused us to fly below the preceding aircraft's flight path and therefore encounter its wake.Suggestions: After learning we were following a heavy aircraft and being cautioned of wake turbulence from ATC; we should have better briefed how to mitigate wake turbulence as a threat. This briefing would include flying slightly higher than the desired vertical approach path. We would also brief a greater emphasis on situational awareness and monitoring vertical flight path management. A better vertical mode selection would keep us at our present altitude until we intercepted the ILS glideslope. For example; we could have turned on VNAV and remained in ALT; instead of continuing to descend towards the final approach fix altitude.