Changing Female clothes to male clothes by Photoshop

Hi. Please always provide the files you're having problems with for we are not going to watch a 25 minutes long video to learn where the costume was downloaded from.

You would need to remove the dark shadows under the breasts and the highlights in the middle of the brests with the healing brush

Well, there is only sampling and clicking when it comes to using the healing brush. How successful this will be depends solely on the texture you're working with.

You could try copy-pasting the texture from the chest area taken from a different item and adjusting its color

- choose polygonal lasso tool and select the lighter area of the breasts;
- choose burn tool, change the range to highlights, exposure to 100%. Change the brush size to the soft 500 px brush. Click in that area, then hold and move. Do that 4 times;
- deselect the selection, make the brush smaller, change range to Shadows, exposure to 2%. Paint in the area circled with orange to make the breast area less round

You can try the same approach with shading or overlay the muscle map, the default one or cc overlay.
When you increase the muscle mass in CAS, you start to see the muscle overlay. It can be found in the game files but I don’t know what it is called.
Here’s a mention of it sims4studio.com/thread/10473/muscles-skin-overlay-template

Or you can extract the normal map from this package and overlay it over your texture
littledica.com/post/639039819572527104/male-muscle-normal-map-skin-detail-dowload-on

drive.google.com/file/d/14xsRBIjqh9uQDURzTyzjozvDmHQwgCKt/view?usp=sharing there is a problem in mesh i guess. Can you check it?
package: drive.google.com/file/d/1Y0BfeF2dCY2EWmlo-H3bnf99a5S2iCqn/view?usp=sharing

I'll try your suggestion and update in here

Okay i did something and it worked hahaha thanks for your helps!