If you are staying in Plockton proper there’s a bit locally to ride. My mates folks once owned the Station Cottage so we spent many a week up there with the bikes (many moons back, remember fondly trashing a trek Y bike there and bombing around on a Proflex with Pace forks)
This is maybe a bit out of date butr the trail we regularly used to ride was this….
Head along the coast path under the cottage (had a green electrical box dumped in front of it last time I visited)towards Duncraig castle, used to be a nice singletrack path under the rail way then up through the rhodedendrums. The up the fire rds and climb the hill with the mast overlooking the village, amazing view from the top (Carn A Bhealaich Mhoir)
Back down the hill passed Achahinach Farm and Loch Achaidh na h-Inich and on through the fire rds and singletrack coming out at a fence above Balmacara, through the fence past the wee monument and down onto the road to Kyle.
Nice way to spent a few hours (assuming its still there and all ridable)