What is the ruling on shaving the beard in response to parental pressure for fear of injustice, and what is the ruling on shortening head hair so that one part is 1 cm and another part is 10 cm?

As long as you have grown your beard and have not suffered any harm, this means that potential harm is not a justification for shaving it. Parental anger is an emotional motive, and you must remain steadfast in growing it out of obedience to Allah, avoiding discord, and relying on Allah, as He says: "And whoever fears Allah - He will make for him a way out And will provide for him from where he does not expect. And whoever relies upon Allah - then He is sufficient for him. Indeed, Allah will accomplish His purpose. Allah has already set for everything a [decreed] extent." and "And whoever fears Allah - He will make for him ease in his matter." while still honoring your parents and apologizing to them gently. As for al-Qaza' (shaving parts of the head and leaving other parts), its ruling applies specifically to shaving, not thinning, unless thinning becomes a symbol of the people of immorality, in which case it is prohibited.