The queen is allowed to use the royal We, to speak for the entire population of the country, then clearly the plural they is used here not the singular they.

If I was I sure as hell hope that an intersectional feminist would slap me upside the face and point out that it is impossible for a person who is trans to be the Queen Of England without being an extremely problematic figure from the perspective of LGTBQ+ people and people fighting colonialism in general (which includes feminism inherently hence the intersectionality).

They would also point out that just using “they” instead of “he or she” does no great injustice to people who identify as one of the two accepted status quo genders because it gets people to immediately retort that a heterosexual person in a position of power was not gendered immediately in discussion and instead referred to with the pronoun “they”, which naturally leads to an opportunity to point out how creepy the structure of the english language is with it’s obsession to immediately box people and identities into male or female.

As a final point I would like to point out that any given trans person who identifies as a Queen is automatically cooler than the Queen Of England. If the trans person can create dope ass baked goods they are automatically 2x as cooler. If they can skateboard too than the effect is exponential leading to a minimum 8x coolness multiplier.