A levels for law

Any "traditionally academic" subjects - pretty much any subject which is primarily assessed by end of year written examination will normally be fine, including STEM subjects and languages. The main things to avoid (or at least avoid taking more than one of) are "applied"/vocational subjects (like Accounting, Music Technology, Textiles, ICT rather than Computer Science, sometimes Business Studies) and creative arts subjects (Music, Art, Drama). The latter subjects tend to be more acceptable to take as a third option, compared with the former.

Additionally avoid excessive curriculum overlap or extremely narrow focus - for example, taking both Economics and Business Studies, or Maths and Further Maths, with only one other subject. Double maths is sometimes acceptable as part of three subjects, but some universities have expressed a preference or requirement FM be taken only as a fourth option in this case. Most of the ~upper quarter of universities as generally "ranked" won't consider Economics and Business Studies as two separate subjects. English Lit and Language taken as two separate subjects may be simialrly regarded, however the "joint" LitLand A-level is usually acceptable. Some universities have in the past regarded English Language to be somewhat "applied"/vocational so it may fall under the previous commentary - I would suggest the combined LitLang option, or just English Lit, if you're considering English in some capacity.

However generally most things are fine - STEM subjects (bio/chem/phys/maths/FM with reference to the above exception), essay based subjects (English Lit/History/Geography/Economics/G&P/Psychology/RS/Sociology/Philosophy/etc, etc) languages (both modern and classical), etc, etc.