Ideally? Everyone.
Unless you exist at every intersection you are writing on and your project is never going in front of another person. Otherwise, absolutely everyone who can afford it should get one regardless of genre, age range, or literary type. Being part of a group doesn’t mean you don’t have internalized racism, homophobia, xenophobia, islamophobia, sexism, classism, anti-semitism, etc.
Should you pay a sensitivity reader? Yes. They are providing a service. They are working from lived experience, so their work is personal and relies on their emotional labor. Most sensitivity readers take extra courses and keep learning about the world so they can stay updated on preferred terms, dog whistles, and the global context that your novel needs to mitigate potential harm.
This is pivotal in creating good representation and not flimsy caricatures. People want stories where marginalized characters are more than assistants to privileged MC’s, killed off, or comic relief. They should also have complex roles, varied interests, and conversations with each other that do not center their empowered counterparts.
Some sensitivity readers allow payment plans to ease the financial burden, but I understand some still cannot afford it. I am not here to shame you for your circumstances. In that case, I recommend finding a few trusted beta readers to assist you. Bonus points if they are from the groups in your book. Follow sensitivity readers and advocates on TikTok and YouTube to learn from them directly. Speaking of the internet, read articles and blog posts about the effects of racism, homophobia, xenophobia, islamophobia, sexism, classism, anti-semitism, etc. When you are able, please tip the people you’ve learned from. Most of them have a Ko-Fi, a Patreon, or their Venmo/ Cash App listed in their bios. It’s a great way to provide direct aid to those you’ve learned from.