In a .NET Core 5 application, how do I dynamically build and change a View *.cshtml page's layout?

In a .NET Core 5 application, how do I dynamically build and change a View *.cshtml page's layout?

I know how to get data in the Controller code, add it to a ViewData["xxx"] and use that data when the View builds the first time, but I don't know how to change the layout.

For example, I have a table that needs to have rows added based on the user's info.

If this were a JavaScript / HTML site, I could make an .ajax call in the JS and build the table dynamically.

How can I dynamically change a *.cshtml View in .NET Core?

Do I send data to the View through a ViewData[*] and use C# to do that?

For example, if the table needs to have three rows with different data for each row, would I put all that in a ViewData[*] and then use that info to build the table within the View?

More importantly, what if I need the layout to change based on user action? 

E.g. what if every time a user clicks a button, another row is added to a table. This would be a row that includes input fields.