Users can add custom search engines to extend functions shown in context menu.

There is a system-wide preference to change available search engines in the context menu for most applications:

Open Menu → Preference in Typora, then click “Open Advanced Settings”.

Open and edit conf.user.json from the “File Explorer”. If there’s no such file, create one.
Modify or set following config into the conf.user.json file, %s will represent the selected text. for example:
"searchService": [
["Search with Google", "https://google.com/search?q=%s"],
["Translate", "http://translate.google.com/?source=osdd#auto|auto|%s"]
["Search with Wikipedia", "https://en.wikipedia.org/wiki/Special:Search/%s"]
]
Note: Default config is:
"searchService": [
["Search with Google", "https://google.com/search?q=%s"],
]
Restart Typora, and then the options from searchService will be available from the context menu.