Ugh it’s so hard! Honestly just try to have patience… our little girl had it bad and just stopped one day. Totally fine with strangers now and turned 1 yesterday.
I have twins and one is that way and the other will go to anyone lol. No advice but it is just a phase and she most likely will grow out of it.
It’s a normal phase! I would suggest following your child’s cues and not forcing any interactions.
I wish I had tips but my kiddo is opposite. Maybe take the kid around people more and socialize and tell them it’s ok to say hi and then you demonstrate. My son wants to say hi to literally anyone he passes. People stop me all the time saying how cute because he smiles and waves to everyone now.