Perpetual Protocol supports limit, stop and trailing orders via a 3rd party interface built on top of the protocol, called APEX—Advanced Perpetual Exchange.
APEX leverages DeFi's trademark composability ("money lego") of DeFi to offer an entirely new way to trade on Perpetual Protocol.
Perpetual Protocol is decentralized and permissionless thanks to open, public blockchains (Ethereum and xDai). However, the same cannot be said of the web, and websites like perp.exchange and any other DeFi web interface are centralized and permissioned.
Therefore, having an independent, 3rd party exchange built on top of Perpetual Protocol is a major advantage for the community and traders using the protocol.
The APEX team works very closely with the main Perpetual Protocol team, and the project was funded directly via the Perpetual DAO. The APEX exchange and smart contract wallet were audited by 3rd party auditors, and tested extensively by the team and community members.
That said, cryptocurrency and DeFi are new technologies in active development. Never trade more than you can afford to lose.