I don't want to shatter your hopes and my experiences might not be reflective of what might happen for you. I did a BA in Philosophy and Politics and MA in Politics and IR - I got a high 2.1 and Merit in both. It's been two years since I finished my MA and I've still yet to find a full-time job. So far I've done one month voluntary (last summer), one part time job 12hrs a week lol (September-December 2018), two temporary jobs (January-March 2019 and mid-April to mid-May). I wanted to work as a parliamentary assistant, caseworker, or researcher for thinktank or analyst for a consultancy. I'm very near to giving up. I can't work in Sainsbury, Primark or Tesco as I'll be seen as 'overqualified' or if I lie/omit my degrees from my CV there will probably be a host of people with other experiences to me. I've probably applied over 100 jobs this year, and I've been to around 7 interviews (including two phone) - this is bearing in mind I don't live in London and had to commute for nearly every interview. I've failed in every single one and didn't even get to the second round for some interviews.
Now, I'm not saying its going to be this hard for you - it might be, it might not, a lot of factors are at play here. In fact, I only feel I got the voluntary job and the temporary job in January because I was an 'ethnic minority'. Whether you'll fare better as a minority or not I don't know... Btw many jobs and organizations I do look at do not have black or Asian people at all. I'm not accusing anybody of being racist here (after all most people who apply probably are white anyway), but I cant help but think of these 'arbitrary' factors about why I cant find a job after so many years....Same with when I attend interviews, I'm starting to think maybe another candidate was better looking, or it was my northern accent that is at fault - I'm probably over-analysing things, but when you're in my position after so many rejections, you point the finger anywhere and everywhere.
I look at the linkedin profile of people at the organizations and companies I want to work for and their CV and experiences aren't too different to mine, sometimes mine is better, sometimes worse. Every job is competitive and I'm unsure what filters are used to weed out 'bad applications' from good ones. People I've graduated with, even from my undergrad years and those with worse grades or those who I know for certain I worked harder than (not bragging), have ended up in better jobs and positions. My point is, job-hunting with a degree in Politics and IR isn't a science, nor a linear career path. In fact depending on your first job experience you may easily ride onto that and end up where you finally do - in however many years. I could've easily ended up in education (teaching) as I was first looking for any job and got interviews as a TA. Didn't work out. But that voluntary job I did was more local-politics based, and since then that is the areas I got other related jobs in.
As the above poster mention, STEM degrees aren't no sure-fire way of landing a job. However, I believe it is a lot easier than a degree in politics, literature or history. If you want my honest opinion, I wish I could rewind the clock and do a STEM degree. I'd probably hate the job I finally get, as I'd want a career with meaning, but at least I'd be more likely to have a job, rather than sitting at home all day scrounging off mum and dad, poor, depressed, playing the ps4, and thinking about my sorry state of affairs most of the day. Not saying it will be like this for you, but don't be surprised if it is..... I know I'm not the only one.