Is it permissible for a graphic designer to design a logo for a competition that requires a civil engineer to apply, by having his brother, who is a civil engineer, submit the design in his name, with the intention of gifting him the prize if he wins, in order to avoid lying about the designer's name?

If the organizing body of the competition stipulates that the contestant must design the logo himself, then it is not permissible to give the logo to your brother for him to submit it in his name, because the Prophet, peace and blessings be upon him, said: "Muslims are bound by their conditions." However, if the body does not stip stipulate that, then there is no harm in giving the logo to your brother for him to participate with it, with the caution of writing down who submitted the logo to avoid lying, or for you to give him the idea for him to design it himself.