The safest and most reliable source is always the official IKEA domain.

Since IKEA removed the download links, you can use internet archives:

While not strictly a PDF, the IKEA app often contains a digital "Scrapbook" feature that mimics the catalog experience, allowing you to save products from the 2023 range directly to a digital list.

If you search Google for "IKEA catalog 2023 pdf," you will find many third-party sites offering downloads. Most of these are: