You could try the blending modes in the layers panel. It's set to normal by default. Changing it to multiply or color burn might make the shape look darker/more red.
Could you post the image and the Layers panel and describe the result you want. It would allow us to provide a more specific recommendation.
Could you provide us with an example of what you're trying to achieve? And a screenshot of what is it you're currently attempting?
As suggested above, you might consider trying blending modes to see if that achieves the desired effect. Here is a screenshot in case you are not sure where to find blending modes in the layers panel. Click the dropdown and you'll see you have a variety of options! You can quickly cycle through the options by holding down Shift and pressing + to go to the next mode or - to go to the previous one. Good luck!