Is a person sinful for raising his voice at his family and calling them ignorant, because they accuse him of being extreme due to his preventing his sister from speaking to someone?

If the addressee is one or both parents, then it is not permissible to raise one's voice at them or address them in an unfitting manner. Repentance and seeking their رضا (pleasure/forgiveness) are obligatory.

If the addressee is other than them, the matter is easier, but this repulsive style should not be used in da'wah (inviting to Islam). Rather, one must be gentle, suppress anger, and be lenient in dialogue to win over hearts. For Allah the Almighty said to Moses and Aaron when He sent them to Pharaoh: "And speak to him a gentle word, that perhaps he may be reminded or fear [Allah]." Gentleness adorns everything, and in the messengers of Allah, there is an excellent example for the da'i (caller to Islam).