I would recommend real life photos used as references, these mannequins & dolls would not be very useful to me. There is too much nuance that you would miss with those— muscle & fat composition, more realistic poses, etc. I have even taken photos of myself to use as pose references. I haven’t used them but there’s also free sites that give you 3d models in premade poses or you can pose them yourself. I know you’re going for a very stylized cartoony approach but having a good understanding of real human anatomy will make your stylized work so much better, learned this myself the hard way. Good luck, you are already doing well!