1, adjust the shoulder strap: check whether the underwear shoulder strap can be adjusted in length. Adjust the shoulder strap to a tight state to improve the position of the neckline. Make sure that the shoulder strap is properly adjusted, so that it will not be too tight to cause discomfort, and it will not be too loose to cause underwear sagging.

2. Use chest patch or chest pad: Use chest patch or chest pad. You can add some padding to the lower part of the chest to make the neckline look higher.