Is it permissible for a son to increase the price of delivery orders and take the excess for himself without his father's knowledge, given that the father does not provide him with a good salary, nor does he allow him to work outside, and the son has financial responsibilities towards his mother?

It is not permissible for you to increase the delivery fee or benefit from it without your father's permission, as you are entrusted by him. You should discuss with him the matter of increasing your salary, and if he does not respond and you find another job that is more beneficial for you, there is no harm in moving to it. Obedience to parents is not obligatory in matters that harm the child, such as if he orders you to work with him while it causes you harm, or prevents you from marrying without an acceptable reason, for obedience is only in what is good and reasonable. Maintain your filial piety towards your father and earn his satisfaction as much as possible.