We used an app for vocab that my husband built for my daughter - it has all 3 ISEE levels populated now.

Here is the link: https://vocab.voyage/

+1 for TestInnovators generally, although our experience is for SSAT, HSPT, and SAT.

Testinnovators.com has been an amazing resource. They have the official ISEE practice tests and a very comprehensive repertoire of practice problems. They also have online tutoring.
Even if you choose a local in person tutor, I highly recommend using TI for practice tests and practice problems

We used the Chernik Group for ISEE test prep. I was very impressed with them. My son did live online sessions.

https://chernikgroup.com/standardized-test-preparation

Does anyone have recommendations for how to prep for the ISEE? My 10 year old has limited experience taking standardized tests and I'd like to get him some structured exposure ahead of taking it sometime over the next year or so. Open to in-person, live online or online/offline self-paced options, even prep books or websites. Many thanks!