All of us have a person; our elder siblings or friends or any one who we are inspired by. For example my elder sister, I love the way she carries herself, her personality, her poise, that I try my best to copy her. So my question is how would i say, any specific word for this? That I'm always trying to imitate her style
You are always emulating her.
to try to equal or excel; imitate with effort to equal or surpass:
to emulate one's father as a concert violinist....
Sons often emulate their fathers.
(Some dictionaries define it as equalling or excelling [not trying to]. So sometimes people use try/trying to emulate to convey this meaning.)
That would be your role model. Merriam-Webster tells us:
someone who another person admires and tries to be like
There are a couple of phrasal verbs you can consider:
model oneself on
Take (someone admired or respected) as an example to copy:
he models himself on rock legend Elvis Presley
pattern yourself on sb/sth (BrE)
to copy something or someone:
She patterns herself on her big sister.
There are common phrases like follow someone's lead or follow/tread in someone's footsteps but they are usually used when you do the same job or the same things in your life as someone else, especially a family member.