go to the funicular station.
get a VTT map.
get on the funicular.
get off at the top.
ride the signposted trails down to the funicular station (there are little signposts, but a map does help/can’t hurt), keep your eyes open for alternative routes.
repeat.
if that doesn’t keep you happy, keep going further left/right than the signposts suggest, keep your eyes open.
my new favourite les arcs/bourg st maurice trail is ‘big gordon’ – you can probably find it on an ign map…
(it’s nothing special, just a few swoopy rooty corners. needs a bit of a pedal though…)