Is it true that what is done by way of Ruqyah and reading Surat Al-Baqarah is of no benefit in the case of a magical knot existing at the doorstep, and that this knot must be untied to facilitate matters?

Sorcery is real, and its effect on the bewitched, by Allah's leave, is what the Quran has spoken of. However, exaggerating the fear of it and attributing every matter to it without real evidence is a reprehensible act. The principle is to deal with matters using apparent, sensory means, coupled with supplication and seeking help from Allah.

Nothing befalls a person except what has been decreed for them. Asserting the existence of sorcery without proof is like casting stones into the unseen. And if it is said that remembrance (dhikr) and recitation are of no benefit in nullifying sorcery, then this is a calumny against Allah; for His words are a cure for every ailment. Continue with the Ruqyah Shariah, and put your trust in Allah.

If the existence of sorcery is confirmed, then if it is possible to extract it without seeking help from sorcerers or charlatans, it is beneficial for healing. Otherwise, continue to treat yourselves with the Quran and remembrance, for there is no cure more beneficial than them.