I'm ftm, and I'm thinking about losing weight to get a more angular body. I'm not overweight, but I have a very feminine shape. I'd imagine since losing weight would reduce my hips and chest, and get me a better jawline, I'd look more masculine. Thinness is typically associated with femininity though, so I'm not sure how much it would help. Any advice?

Losing weight for everyone will improve your appearance.

Fat deposits for men are a different pattern than for women, unless we get morbidly obese and then we all seem to look the same.

For a FTM that is not overweight, the only way to get a more masculine body by building more muscle mass in your body.   The best way to do this is by taking Testosterone, working out in the gym and eating much more protein than you are now doing.