Looking for a plugin for menu inside page

This is a basic functionality that is now provided by almost all themes. You can manage such menus in the backend under Appearance > Menu or – in the case of modern FSE themes or Elementor – also in PageBuilder.

With Gutenberg (aka Block Editor, used for FSE themes) you can manage such menus as shown here: https://www.ads-software.com/documentation/article/navigation-block/

With Elementor: https://elementor.com/help/the-menu-widget/

Thanks for the reply.

But I need to show the dropdown inside the page content. It will different for each page.

For eg:

Page kjkldLADLAdLDLAdLKD;Lk;lKD;Lkdl;KD;L

Dropdown menu

page contentjdKDdm.DMA.

Oh, you mean a dropdown, not a menu. That would be possible with the Categories block, for example, see: https://www.ads-software.com/documentation/article/categories-block/ – there is an option to display the categories as a dropdown (aka select element).