Can I switch courses at my firm on results day?

The uni I want to firm gave me an alternative offer, which I’m suspecting to be because of the course being full due to how competitive it is.
The rejection was pre interview for DR to TR and at my interview there were several other candidates who had also originally applied for DR but were placed onto TR due to applying later (December/January).
Would I be able to switch courses on results day if there are spaces available (indicated by the course being in clearing)?

Its possible but unlikely - and its very risky picking any Uni/course in the vague hope that you might get to switch courses later. You could just get stuck on the original course.
Ask for feedback - ie. why did you not get an offer for the original course? If this is something fixable like a weak PS, predicted grades, the right GCSEs or lack of relevant experience, then take a gap year, work on those things, and reapply.
And btw, Unis are not allowed to 'prefer' those who apply earlier. If you apply before the Jan deadline they *must* give you 'equal consideration', its part of their legal contract with UCAS. if you have any real evidence of later applicants being rejected this reason (not just 'my mates assumed this or said it to me to make me feel better about being rejected') then you need to talk to UCAS immediately.

Do you think rejecting my offers and reapplying would be better? I don’t really mind the course I’ve been placed on bcs I have the same career and pay opportunities just with a slightly different profession, it’s just the mental heath aspect I’m worried abt tbh. Also could you elaborate on the risks?