YYMV clearly, but some labs are definitely non-social. My time as a PhD student was one of the most lonely and isolating experiences I have had. There are reasons PhDs have higher incidents of poor mental health than gen pop. For me, lab mates cliqued together (by language), and for those that came in, they didn’t follow any social considerations including saying hi despite my efforts at inclusion/friendliness. Review online lists on downsides to PhD programs to weigh what works for you.