For me, "redefining sex" has meant moving from a heteronormative perspective to a more fluid one. I include self-pleasure as sex with myself. I include sex with my female partner, which is sometimes penetrative, sometimes not. Typically, we both reach orgasm, but not always. Orgasms aren't the definition of sex. Penis in vagina isn't the definition of sex. Acts of consensual intimacy where the goal is pleasure and connectiveness with a partner is where my re-definition lies. Though, that is a very personal definition. I also include group sex or BDSM activities, where the goal may be pleasure and the typical "intimacy" may not be present
I want to ask for more context for this question because redefining sex is subjective... redefining sex for myself would be bulldozing the western narrative of sex being goal oriented toward orgasm as a singular event and prioritizing my male partners orgasm over my own. Redefining sexuality would incorporate greater sensuality over a longer period. Like a weekend of engaging as opposed to an hour or 2.
To reimagine sex beyond the heteronormative, and trying to tease apart the relationship, or lack thereof, between identity and practice.