WorldCat will find you books in other libraries worldwide. Coverage is uneven; e.g. there are some major African cities with no libraries included.
The SIA librarians will help you find books and access libraries anywhere in the world: though please note our knowledge of many countries is limited.
London and the rest of the UK
Library Hub Discover will find you books in other libraries in the UK (plus Dublin).
Library Hub Discover does not tell you which of the libraries it lists you can access, or how to arrange a visit. For this info for London, see:libraries in London. For other cities in the UK, consult the SIA librarians.
Key libraries in London for luxury studies
and also the following (which are not included in Library Hub Discover):