The free school meals/care questions tend to be from organisations who try to prioritise hiring people from disadvantaged or less privileged backgrounds. Some organisations also extend this to ex Armed Forces personnel, prison leavers, and other groups who may face barriers in finding employment.
Disability questions are asked so that if you meet the minimum essential requirements for the role, you will be guaranteed an interview under the Job Interview Guarantee Scheme, and also so that if there are any reasonably adjustments needed, they can be taken into consideration for interview/working environment and practises. Also disclosing access needs at application stage means that preliminary applications can be made for specialised equipment under the Access To Work scheme, which usually takes a few months to get the funding for, so the earlier it can be flagged, the faster you or a future colleague can have something like Dragon text to speech software, an ergonomic chair, or even a sign language interpreter at a job interview.
The trans/gender/sexuality questions will be for (confidential) EDI monitoring so they can make sure their workforce is representative/in line with general statistics.
The one about caring responsibilities in my experience is so they can be mindful of other commitments you may have outside of work.
They may seem blunt or clunky but they tend to be an organisations way of ensuring that they have inclusive hiring practises and working environments, rather than a tool to ‘exclude’ candidates. I often recommend that organisations add a one liner to the top of those forms to explain why the questions are being asked in order to reassure candidates, because they do seem to be frequently interpreted from a ‘fear of exclusion’ viewpoint rather than a ‘reassurance about inclusion’ one if they’re just laid out cold like this.
[Source: I work in inclusive recruitment policy and equality impact analysis for government organisations]