If you have a large minky/velvet/cuddle blanket in a light color, that always makes an eyecatching plain solid background that keeps one's eyes on the doll(s) without distraction of busy backgrounds.
Also, slightly bend the doll forward at the hips/waist and have them looking down as much as possible. Then take slightly upwards photos which gives them the best angles and makes their proportions better in the camera. If you take just straight on, they usually end up looking too short legged. This camera angle 'trick' gives them back their proportions somehow.
For settings, instead of auto, I choose 'Portrait' for dolls and people. It kind of blurs the background but keeps the subject in focus. I don't know if you have that setting on a phone, though. Also, don't take photos at the highest size as that's usually too big for good internet viewing. I choose the small-medium option with highest quality, which actually ends up taking the best photos of dolls because it doesn't blur or 'expand' their small lines of the eyes and enlarge them. The small-medium resolution takes very large enough pics without blurring out.