What is the ruling of Islamic law regarding the eldest brother's refusal to distribute the inheritance with the aim of growing the money, while spending it on some heirs without the consent of the others, and is the money spent considered unlawful for those who receive it due to the lack of consent from all heirs?

Neither your brother nor any other heir has the right to prevent the division of the inheritance under the pretext of developing it, or spending from it on some heirs to the exclusion of others. The estate is a right for all heirs from the date of the deceased's death, and every heir owns their rightful share of it. It is not permissible for anyone to take more than their rightful share without the consent of the remaining heirs. What your brother is doing, spending on some heirs to the exclusion of others, is forbidden, and those on whom he spends are not entitled to take more than their rightful share. You must fear Allah Almighty, reconcile, and resort to Islamic law. If this is not achieved, the matter must be brought before the Sharia (definition) court.