What type of port scan is similar to a syn scan and is risky to use because it relies on the attacked computer's os?

Port scanning is used by security testers and hackers to check the security and vulnerabilities of a network.
The connect scan is similar to a syn scan and is risky to use because it relies on the attacked computer's OS. The connect scan includes Nmap asking its underlying Operating network to establish a connection with the target server by issuing the “connect” system call.