Duplicate Line(s) Keyboard Shortcut

Yes but the fundamental difference in Obsidian is that Readable line length‑setting is either on or off and Obsidian doesn’t offer any feature to toggle this setting easily on the fly. Line duplication editing action makes most sense in case of Readable line length‑setting is turned off.

Related feature requests about Readable line length—note that some of them might be duplicate feature requests @CawlinTeffid :

https://forum.obsidian.md/t/hotkey-for-toggling-readable-line-lenght/9441
https://forum.obsidian.md/t/enable-readable-line-length-in-markdown-preview-mode-but-not-in-editing-mode/25224