Security

So you need to look at the Laws that apply in the area where their servers are located and then you will have an answer.

If the Local Laws in the State/Country where their servers are do not allow them not to pass on data to the Authorities then they are not any more secure than the Laws Allow.

DuckDuckGo is a private search engine. It is adamant about spreading privacy around the internet. However, there is one issue I discovered that raises privacy concerns. Your search terms, while they may be sent over your network in an encrypted form, show up in plain text in browsing history.
DDG may work well for reducing advertiser tracking, avoiding filter bubbles, and limiting data profiling, however, it may not offer the protection from surveillance organizations that some think.

Duck duck go is a browser and it does not track your searches like google and bing.
Also, there are no ads which make it a good browser for privacy.
However, your ISP can still track your searches because the data you search is not being encrypted.

To Encrypt the data use a VPN. It encrypts the public and private IP making it almost impossible for your ISP to track your searches.

What you can do is use both Duck ducl go and VPN for enhanced security