This page of the guide to Far Cry 6 explains how to get a bow and crossbow. Both of these weapons can be helpful if you want to take enemies down stealthily.
Example Bullseye Bow
Several different bows are available in Far Cry 6 , including regular ones (purchasable from select merchants or found as random loot), and unique weapons.
One of the unique bows is the Bullseye Bow. To find it, you must go to the small enemy location, marked in the image above, in southwestern Sierra Perdida in El Este.
The bow will be in a large chest in one of the cages. Its main unique features are dealing more damage to enemies below you (attack them from high ground, rooftops, vantage points, etc.) and charging Supremos faster with headshots.
Example La Clavadora crossbow
You can purchase the crossbow from Juan during the Yaran story called Supremacy. Juan's main store is located on Libertad Island, and to buy the items he offers you must pay with depleted uranium (a rare resource found in enemy bases).
The crossbow costs 100 depleted uranium. It is one of the so-called Resolver Weapons.