What can I do about the sagging lower eyelid and cheek (left side)? (Photo)

It's difficult to say without the benefit of a formal evaluation. This is my expertise and a huge portion of my practice. Asymmetry is normal and expected. See an expert who does facial shaping with surgical and non surgical methods to get a comprehensive option. Best, Dr. Emer.

It does seem that you have ptosis of your midface on the left side. Possibly due to chronic pulling or sleeping on that side or a past trauma, etc... A midface lift on the left side would help improve the volume loss of the left cheek and lessen the subsequent nasolabial fold created by the midface descent. This may help improve your lid cheek junction transition by resuspending your lower eyelid at the same time.

From your photos it appears you would have the best results from a combination of treatments. Fillers can be used to help improve asymmetry as well as replace lost volume. Morpheus8 treatments can improve overall skin tone and texture. See a board certified plastic surgeon near you to learn more.