What would my chances be of getting into Oxford Law?

If you want the best chance, the LNAT is very important for Oxford in particular. If you don't do well for the LNAT you may not even get a chance for interview (so no chance to impress them at interview).
The law work experience is secondary. I had friends with weak portfolios and no law work experience but got in because they did well for the LNAT (definitely try all the official LNAT practice papers on their website, and you can get further lnat guidebooks and tips from amazon, like the complete lnat guide by Leslie and Kian Yang has some really good tips, and the one by mark shepherd is old and a bit outdated but still pretty good too)

the LNAT can help you I agree but it is ultimately a holistic assessment (with contextual GCSEs or equivalent the central focus)

I’m in my final year of secondary school in Scotland and i’m doing 3 Advanced highers (two of which are essay based) and a higher. I’m looking to apply to Oxford for 2026 entry. Let’s say I achieve the entry requirements. Would I have a good chance of getting in if I: 1) Get a really good LNAT score and revise hard for it, 2) Do well on the interview. I have Law work experience but apart from that not a lot of Law related extracurriculars.
However, my uncle graduated from Oxford and my cousin is there doing English Lit, but I don’t know if that matters. So let’s say I achieve all of the aforementioned things, would I have a good chance of getting in?? And if not, what would affect my application the most?

GCSEs are not the central focus in the Oxford admission process, as is clearly explained on the university's website.

GCSEs are central to the Law admissions process. Combined with LNAT and contextualisation factors. Work experience is not relevant.

GCSEs are central to the Law admissions process. Combined with LNAT and contextualisation factors. Work experience is not relevant.

Work experience is relevant as some applicants have been asked questions about it during the interviews at both Oxford and Cambridge.

On what basis do you make that assertion about GCSEs?

It was explained in the Open Day talk.
Yes, it's holistic and they contextualise. But GCSEs are a very important part of that. "Central" isn't perhaps a helpful way to think about it. There are multiple factors that are considered together, some are particularly important. GCSEs are one of them. Work experience is not one of them.

So, in other words, GCSEs are not central. That accords with what Oxford says about GCSEs on its website.
"GCSEs
GCSEs will be taken into account when we consider your application but they are just one aspect that we look at. GCSE results will be considered alongside your personal statement, academic reference, predicted grades and performance in any written work or written test required for your course.
If you are shortlisted, your performance in interviews will also be taken into account. Higher grades at GCSE can help to make your application more competitive, and successful applicants typically have a high proportion of 7,8 and 9 grades. However, we do look at GCSE grades in context.
If you feel that you did less well in your GCSEs than you might otherwise have done because of extenuating circumstances, you may still be able to make a competitive application. Examples would include disruption caused by change of school or system, severe discontinuity of teachers, bereavement, and debilitating illness.
We take care to treat each application individually and would always take such extenuating circumstances into account, if they are brought to our attention. You may like to mention any such circumstances in your personal statement, and your referee should make sure to mention them clearly in their reference.
If for any reason this is not possible, then we would advise you to contact the college you applied to (or are assigned to if making an open application) once they are likely to have received your application. This is likely to be around the end of October.
For those who were due to take GCSEs in 2020 and 2021, we will take into account the difficult circumstances in which these grades were issued when we assess your application. Please follow our advice about personal statements and academic references which we update for each year of entry.
Tutors will want to see how you improve your academic performance after your GCSEs and that you do well in your A-levels or other equivalent qualifications.
We recommend that candidates take those GCSE subjects that they enjoy the most and are confident in achieving good grades in."