If God is going to do his will regardless, what is the point of asking him for anything? Does praying actually change what happens?

“Pardon, I beseech thee, the iniquity of this people according unto the greatness of thy mercy, and as thou hast forgiven this people, from Egypt even until now. And the LORD said, I have pardoned according to thy word:”

Israel has refused to enter the land and God declares he will disinherit them. Moses stands in the gap and argues, appealing to God's reputation among the nations and to his steadfast love, and asks for pardon. The reply is short: I have pardoned according to thy word. Whatever else is happening in that exchange, the text is entirely unembarrassed about presenting prayer as something that counts in the outcome.

“Saying, Father, if thou be willing, remove this cup from me: nevertheless not my will, but thine, be done.”

In the garden, hours before his arrest, Jesus asks for the cup to be taken away and then submits to his Father's will. Both halves of that are prayer. He asks plainly for what he wants, knowing the answer, and he does not treat submission as a reason to stay quiet. Luke adds that as it grew harder he prayed more earnestly, not less.