Personally, I hate it when people answer a fair question by saying "go read this book," so what I'm going to do is give you the essence of two books that were really important for me and then urge you to go read them. If that's your thing.
At 25% of your final word length there's a thing called THE END OF THE BEGINNING. This is usually a very clear line: Your protagonist moves from a familiar world to an unfamiliar world, and a new and difficult situation. You can also call this the end of Act I. Often (not always) the goal becomes clear here. [Restless Dorothy, unhappy with Miss Gulch's persecution of Toto, is caught up in a twister and enters the magical land of OZ. Because she knows her aunt is sick, though, she wants to go home.]
At 50% of your final word length there's a thing called the HALFWAY POINT. Your protagonist has the chance to back down from the goal, but doesn't. Instead, he/she recommits. This is the point of no return. [Dorothy reaches the Emerald City, but finds that she has to go on a quest to get the broom of the Wicked Witch if she wants to get back to Kansas. She agrees and begins the quest.]
At 65-75% of your final word length, there's a CRISIS. The protagonist has the choice to either resist the difficult situation and become a victim, or yield to what is, be transformed and become a victor. After that decision (in a murky bit of terrain where the energy drops off a bit), there's a transition out of Act II and into act III. This dividing line is harder for me to spot than the dividing line between Act I and Act II, but it always follows the crisis. I think it may be less of a line than a slow fade, personally. [Under attack, Dorothy takes action and throws water at the flaming Scarecrow ... but also douses the Wicked Witch, melting her. She then heads back to OZ with the broom in hand.]
At 90-95% of your final word length, there's a CLIMAX (also called a THIRD-ACT TWIST) where the story reaches its highest point of energy and the protagonist uses a special skill or ability to overcome his/her obstacle. [Dorothy is left behind when the balloon flies off without her. She reaches her lowest point, and returning to Kansas seems impossible. Then Glinda appears and it turns out Dorothy's real obstacle was internal: She could have gone home all along, but she didn't yet realize "there's no place like home."]
At something close to 100% of your final word length, there's a RESOLUTION and evidence of the emotional growth of the protagonist. [Dorothy achieves her objective and makes it home. There really is no place like home!]
I offer all this detail because it's obvious, in looking at a well-crafted plot like this, that you have to know what Dorothy's objective is going to be in order to write the CLIMAX and RESOLUTION, which is what you asked about.
These plot point names (except for the THIRD-ACT TWIST) are from Martha Alderson's indispensable book THE PLOT WHISPERER. I analyzed the Wizard of Oz story using her template. (If she did it somewhere else, I couldn't find it online.) You should read Alderson. But if you choose not to, you can use what I sketched out here.
This part requires you to answer certain questions about your character. Ask yourself the questions and then come up with your best answer, in writing. Then check what you've written with someone who supports you and is familiar with your work and will challenge you. That's the only way to get it right. It takes some work.