Yes. A person soul or more likely their unconscious egoic shadow self can and so send out malicious energy.

Yes it can have physical effects on the recipient. It depends on how much energy is being exchanged or transferred or siphoned. Energy vamping can leave a victim feeling woozy and foggy brained.

Sometimes if you are sensitive enough or warded enough you can feel spells or hexes being cast. The trick is mainly mental with that one. Narcissistic people are well known for bypassing hexes or curse due to their self identity and sense of over confidence and God identity.

And yeah a person can do all this and be utterly clueless outside the fact that they have terrible luck with friends and relationships. Imo it stems from serious need to do shadow work and integrate.

Hope this makes sense. It's just my two cents and personal experiences.