Highly unlikely. The Oxford interviews are the “meat and potatoes” of the process and if you genuinely perform poorly (which isn’t necessarily the same as you thinking you did badly) you’re very unlikely to get an offer. Things like your PS and any admissions tests a subject may have are designed to filter out the best candidates for interview and once you get there a stellar PS and exemplary admissions test result is probably not going to save you if your interview performance is bad. Because remember, Oxford has a very unique style of teaching and so a large chunk of what the tutors are assessing is whether you would thrive under that system. And there are loads of ridiculously clever people who wouldn’t, which is why every year you still see people getting rejected who have straight A*s and loads of other stuff. So focus on all parts of your application but special attention to the interviews and the best way you can prepare for them!