Wikipedia's actually pretty good about this iirc, at least aside from the whole 'if they were notable before transitioning, their deadname must be there' thing, but please correct me if I am wrong and/or a dumb cis boy please trans comrades :trans-heart:

Gender identity

Refer to any person whose gender might be questioned with gendered words (e.g. pronouns, "man/woman", "waiter/waitress") that reflect the person's latest expressed gender self-identification as reported in the most recent reliable sources, even if it does not match what is most common in sources. This holds for any phase of the person's life, unless they have indicated a preference otherwise.

If a living transgender or non-binary person was not notable under a former name (a "deadname"), it should not be included in any page (including lists, redirects, disambiguation pages, category names, templates, etc), even in quotations, even if reliable sourcing exists. Treat the pre-notability name as a privacy interest separate from (and often greater than) the person's current name.

From Laverne Cox, not notable under prior name: Laverne Cox (born May 29, 1972) ...

A living transgender or non-binary person's former name should be included in the lead sentence of their main biographical article only if they were notable under it; introduce the name with "born" or "formerly":

From Chelsea Manning, notable under prior name: Chelsea Elizabeth Manning (born Bradley Edward Manning; December 17, 1987) ... From Elliot Page, notable under prior name: Elliot Page (formerly Ellen Page; born February 21, 1987) ...

Outside the main biographical article, generally do not discuss in detail changes of a person's name or gender presentation unless pertinent. Where a person's gender may come as a surprise, explain it on first occurrence, without overemphasis. Avoid confusing constructions (Jane Doe fathered a child) by rewriting (e.g., Jane Doe became a parent). In articles on works or other activity by a living trans or non-binary person before transition, use their current name as the primary name (in prose, tables, lists, infoboxes, etc.), unless they prefer their former name be used for past events. If they were notable under the name by which they were credited for the work or other activity, provide it in a parenthetical or footnote on first reference; add more parentheticals or footnotes only if needed to avoid confusion. Gender identity