In the aftermath of Queen Elizabeth II's death, some news outlets had started speculating what kind of monarch her successor - King Charles III - would be.
Much has been said about King Charles' more outspoken positions on certain policy areas, such as the environment and immigration. Likewise, his heir apparent - Prince William - is also outspoken on social issues like mental health.
This leads to questions as to whether he - as the monarch - is permitted to express opinions on these policy areas, provided that he does not interfere with the daily functioning of the Government or Parliament. For example, he may publicly begrudge the Government doing little on mitigating climate crisis, but he nevertheless must ratify bills which enable such policy.
Bear in mind that this is not without precedent. For example, Germany's head of state (i.e. German President) is a ceremonial office, but is still culturally permitted to express political positions to guide public discourse. Evidently, Germany has not burned to the ground just because their head of state has opinions.