Organize the position of the charts on the page

Question

I have the following snippet of code:

observeEvent(input$btn_enter, {
      for (indicator in isolate(input$indicators)) {
        appendTab(
          inputId = "tabs",
          tabPanel(
            indicator,
            mainPanel(
              column(width = 4,
                plotOutput(paste0("chart_1_", make.names(indicator))),
                plotlyOutput(paste0("chart_2_", make.names(indicator)))
                ),
              column(width = 4,
                plotOutput(paste0("chart_3_", make.names(indicator)))
                )
            )
          )
        )
      }
  },
  ignoreInit = TRUE)

I would like to change my code so that:

• fit the two columns to the width of my page (each column takes up half the page);
• chart_3_ should occupy the entire right side of the page (and not just the top right). Can anyone give me some suggestions? Thanks in advance.