how can congress use it power of the purse to impact the agenda of the executive branch

congress could stop programs or plans proposed by the executive branch from being implemeted
congress could eliminate executive department or agencies
congress could force the executiive branch to fund its own departments and agencies
congress could encourage the executive branch to find certain department or agencies

Congress can also use its power of the purse to place restrictions or conditions on the funding allocated to certain programs or initiatives proposed by the executive branch. For example, Congress could attach stipulations to appropriations bills that require the executive branch to comply with certain policies or regulations, or redirect funds towards different priorities. By controlling the allocation of funding, Congress can ultimately influence the agenda and priorities of the executive branch.