Are the lines on your neck circular "necklace" line or more the criss-crossy crepey lines? As a general rule, these need different solutions. The necklace lines are related more to muscle movement in the neck over time and can be softened and reduced by a few drops of Botox. There isn’t any cream, unfortunately, that will make those look better.
If the lines on your neck are more crepey, fine lines, then yes, over 6-9 months, treating the area with a gentle Retinol (Vitamin A cousin), and an antioxidant can help. The neck skin is much more sensitive so many of the products for the face are too irritating here. Sometimes products formulated for the eye area are nice on the neck. Try the Neostrata Eye Cream (beta-hydroxy acid) or a Renova (prescription Vitamin A) but dilute it out 1:2 or 1:3 with your moisturizer at night. Then the Replenix Cream (green tea antioxidant) under your sunscreen in the morning. Try the same strategy for your chest. Just remember though that if there is a lot of sun damage, there isn’t any cream that will make a huge difference. You may need lasers eventually.