You're right to be curious, as the answer is that it will be completely different for everyone as our bodies store fat/muscle in varying amounts and in different places!
For example, a skinny girl who's suffering from a lot of stress may be a very low weight but is likely holding her fat stores around her tummy (thank you cortisol ¬¬). Her lowest weight (if we say she's 5' 8) could be somewhere around 100lbs, and it would look like that too providing she wasn't in a bikini!
Another example would be an athlete whose BF% was very low, to the point of being unhealthy, but her weight was classed as normal. She probably has a flat stomach without an inch to pinch, but still some fat stores hidden in the thighs/very upper arms. If we say this girl is 5' 8 too, her muscle mass and bone density would be much higher due to the levels of exercise. Her lowest weight will probably be around 120lbs without sacrificing her performance or fertility. She wouldn't look this weight, she would probably look around 100lbs too!
Appearance isn't everything girls
hard to accept (believe me I know!) but it's very true.