Hi Neha thanks for posting on the community! 

While there isn't a way to automatically highlight the tables connected to a particular table in your ERD you can manually adjust the style of each table from the properties bar as explained in the Add Style section of the ERD article.

If you prefer you could instead set up Conditional Formatting rules to style specific shapes based off of the shape data or the text they contain etc. Details and instructions on setting up Conditional Formatting rules can be found in the Conditional Formatting and Icon Sets article. Please note that this will require setting up rules based off of what is contained in the tables you are highlighting so this still isn't a way to automatically style all the shapes attached to a particular shape.

If you would like to pass on your idea would you please add it to our feature request form? Ideas submitted here are passed onto our product development team for their consideration. Thanks!

Is this still not developed? I have a similar situation, the ERD is huge schema I want to highlight the selected Entity and its connected Entities, and the corresponding lines related to it. But I tied applying the Conditional Formatting rule similar to this, but it only gets applied to the Shapes in the diagram not to the Entities of the ERD.

Highlighting connected shapes using conditional formatting & formulas | Community

Hi ​@Saumya, thanks for chiming in! 

Unfortunately, this isn’t currently supported in Lucid, but we’re very interested in your feedback and committed to continually improving our products. It seems like no one has submitted this idea yet, so please feel free to create one of your own and be sure to include details about your use case or what you’d like to see in this experience. This will also allow other users with similar requests to discover and upvote it, then add details of their own.

For more information on how Lucid manages feedback via this community, take a look at this post.

Finally, could you please provide more details and screenshots regarding the issue you are encountering with Conditional Formatting? Just to make sure that we are on the same page, I would also recommend going through our Add conditional formatting in Lucidchart article.

Cheers!