Don't panic OP, I can feel your anxiety dripping from your post and it really isn't a catastrophe - not saying it's not hard out there, but there are jobs, 100% and you will be able to get one. If your main concern is feeding yourself/paying your way, and you are able to keep living with your mum, even a minimum wage job would do that and would be a fine stop-gap while you consider what you really want to do.
I'd also take it one step at a time and think small, don't panic about needing all the answers to where you'll live/how you'll find your dream job/how you'll move out of home/what will happen with Covid all at once, it's easy to find it overwhelming. Make a list of small steps, e.g. see careers adviser, do quiz, make list of possible graduate schemes, consider work experience placement etc., and tick at least one off the list per week, you will feel more in control this way!
I was very much like you when I graduated uni and my major regret is that I allowed myself to be rushed into major life decisions involving relocation/commitment to a career path straight after graduating when in reality there was no need to panic and hurry - I allowed myself to be highly influenced by a number of unhelpful factors/people that in hindsight really shouldn't have had the impact on me they did (such as peer pressure/an arsehole ex boyfriend/my parents/other people's parents/useless uni career service) and I was convinced of 3 things, none of which I now think was true, namely (a) it would be an absolute disaster if I had to move back home even for a few months (b) I needed to get a 'graduate' job straight out of uni or my degree was a waste of time and money (c) if I didn't know what I wanted to do in life by the time I left uni, I'd never know. All bollocks as it turns out and pretty poor as a foundation for a life strategy! It all worked out OK for me in the end but I really wish I'd just taken my time, considered my options, done my research, perhaps taken some temp jobs - one big issue for new graduates is that naturally you really lack work experience, but without spending some time in the 'proper' workplace it's really hard to know the range of jobs that are out there and what will suit you - e.g. I just lumped all 'office jobs' in my mind into one vaguely homogenous grey corporate lump of things you'd only do for the money, but there are so many different and interesting jobs that fall under that umbrella and in a range of different sectors and companies too - it isn't all the obvious things that spring to mind, accountancy and IT for instance. Even within those fields there are fascinating jobs that do good things for the world, if that's a driver/concern for you. The same goes in loads of different fields - science, health, education, media for instance. You may come to a conclusion that actually you need to do more study or spend some time gaining work experience - that's fine, you are 21, you literally have your whole life ahead of you. I know it feels like a step backwards but it really wouldn't be the worst thing to have moving home as a stop gap measure ready as your plan 'B' - I think covid may well be actually quite a good thing in one way, because home/remote working is so much more the norm, you may be able to postpone making any decisions about relocation longer than would have been the case a few years ago - you can look at jobs based virtually anywhere in the world so long as you can work remotely from your mum's house for at least a few months before needing to commit to moving to a strange city etc, which is a super opportunity if you can only bring yourself to see it that way 
! Good luck!