Tableau can create the usual Trend Lines (Linear, Logarithmic, Exponential, Polynomial, Power) using the option with the same name in the Analytics bar and dragging and dropping it onto the view:
If the Trend Line option is not available for selection in the sidebar, this usually is because you need both axes to be measures, or a date and a measure. This will be indicated when hovering over the grayed-out option.
For instance, using the Global Superstore dataset, we can add Profit to rows, Sales to columns, Order ID to Detail marks, and filtering for orders where Order Profitable? is Profitable. Then, we can drop the Trend Line onto the Linear icon on the visualization. By doing this, we'll get the following output:
Hovering over the line will show the tooltip with the equation and the R2 and P values, which will help you identify whether the trend is relevant or not.
If you need to edit the trend line or change the parameters, you can choose the Edit option in the tooltip to go to the Trend Line Options window.
Now, it's very easy to identify trends with a few clicks, thanks to the power of Tableau.