Doll vaginal and anal cavities are made snug to accommodate any insertion. The silicone or TPE flesh is soft, slippery (when you use the appropriate lubricant), and very elastic. Any water-based lubricants should be applied to ease entry. Doll’s oral cavities contain soft silicone tongue and teeth (paid add-on on most models). The oral cavity is as snug as the doll’s other entries. All three cavities allow deep insertions although oral capacity varies by face type.
However, big cautious if you have HDS (Horse Dick Syndrome), if you are diagnosed with such a condition, please pick a doll as big as possible. Big dolls tend to have bigger orifices.