Finding bounties that compensate in bitcoin are harder to find. Varries depending on task. Usually they need a problem fixed, help acquiring new customers, or promoting an ICO. Rather than negotiating before hand on terms and conditions like you would for freelancing, bounties are open to the public. Whoever finishes the task at hand gets compensated. Similar to how bounty postings in the old west used to work.
Some bounties are one time only deals, such as fixing a bug, so who ever completes it first is the only one who gets compensated. However, most bounties are repeatable, such as bringing in referrals or promoting their product on social media.
Generally, most bounties will compensate you in alt-coins as opposed to Bitcoin and Etherium. Companies that compensate in bitcoin are highly competitive, but are still possible to find. The payout varies depending on the task required. That being said, the payout varies depending on the job. Some bounties can be worth only a few dollars, whereas others can be thousands of dollars. Hell, there is even a 10 million dollar bounty open by Binance to catch hackers.
As mentioned previously, the Reddit Jobs4bitcoin has a few bounties available. They are few and far between normal job postings, but Reddit makes filtering them easy with a simple search. Write to Earn Bitcoins on Yours. Write content on your own schedule.