Is it permissible to replace waqf land belonging to a mosque in a distant area with another plot of land owned by a man that is closer to the mosque? And is it a condition that it be of the same size, or is it permissible for it to be of a larger size if the man requests that?

It is permissible to sell a distant waqf land and buy land closer to the mosque, or to exchange it for something better, even if it exceeds its equivalent value, because the purpose of the waqf is the benefit it provides, not its specific type. Imam Ahmad and Ibn Taymiyyah permitted exchanging a waqf for an alternative if its benefit became interrupted. They cited the action of Umar ibn al-Khattab in exchanging the old Kufa mosque as evidence, and the permissibility of relocating or selling a mosque to build another if it becomes dilapidated and is no longer needed. It is also commendable to invite the landowner to donate it so that his reward may be counted with Allah.