Well, let's see. This is from CNN.com in 2021:
A 2007 study from the University of California, Irvine, found that incarcerated transgender people were 13 times more likely to be sexually assaulted than a random sample of incarcerated men. Fifty-nine percent of transgender prisoners reported having been sexually assaulted within a California correctional facility compared to just 4.4% of the incarcerated population as a whole.
A 2019 meta-study published in the Intl Journal of Transgenderism found this result:
Despite these recent acknowledgements, research suggests that prisoners who transgress heteronormative sex, sexuality and gender boundaries are at higher risk of experiencing bullying, violence, harassment, coercion, and sexual assault compared to other prisoners (Atabay, 2009; Australian Human Rights Commission, 2015; Blight, 2000; Carr et al., 2016; Dunn, 2013; Gatherer et al., 2014; Grant et al., 2011; Jenness & Fenstermaker, 2014; Jenness, Maxson, Matsuda, & Sumner, 2007a; Jenness et al., 2007b; Meyer et al., 2017; National LGBTI Health Alliance, 2012; UNAIDS, 2014; White Hughto et al., 2018; Wilson et al., 2017). For example, lesbian, gay, and bisexual prisoners are more likely to experience sexual assault than their heterosexual counterparts (from other inmates), and the likelihood is even greater for transgender women inmates (Beck, Berzofsky, Caspar, & Krebs, 2013; Blight, 2000; Clark et al., 2017; Carr et al., 2016; Jenness et al., 2007b; Oparah, 2012; von Dresner, Underwood, Suarez, & Franklin, 2013; White Hughto et al., 2018; Wilson et al., 2017).
All those studies were linked to in the footnotes, I think; I don't have time to click on them all.