Outdoor problems have no coloured holds, so you read the topo: find the start holds, check for sds (sit start), and see whether the finish is a final hold or a top out. If nothing says how to start, the Fontainebleau convention is a standing start from the ground. Etiquette is about keeping access: park where you're meant to, keep quiet, put pads on durable ground, brush off chalk and tick marks before you leave, stay off wet sandstone, and carry out all trash and any pads you stashed.
Taiwan has about ten published bouldering areas and two bilingual guidebooks. Without a car, and climbing around V2 in the gym, start at Chung Tai Chan Monastery in Beitou: about 17 minutes on foot from MRT Qiyan Station, with flat ground and low boulders. With a car, Li-Yang near Taichung has mostly good riverbed landings and problems mostly from V0 to V5. None of these areas has a bouldering notice from a land manager that we could find, which does not mean anything goes. Taiwan is wet: mountain areas get overgrown with moss again, and riverbed areas depend on the weather and the river.
There is no fixed height for a highball: some say 10 feet (about 3 m), Climbing calls 15 feet (about 4.5 m) the "gym line", and others argue the landing and the height of the crux matter more than total height. Past a certain point, neither pads nor spotters can hold a falling climber; Climbing says don't even try to catch someone from 10 feet. Several AAC accident reports involve climbers stuck at the top out whose holds broke as they tried to downclimb. For most people the default should be a toprope: less gear, one partner, and bouldering legend John Gill did it too.