I’ve used Purify on iPhone & iPad for a long time. It seems to work very well, has no issues and it’s free.
Purify: Block Ads and Tracking by Chris Aljoudi
https://apps.apple.com/us/app/purify...g/id1030156203
UPDATE — I see this one now costs $1.99. Here are some reviews (FWIW)
https://theappfactor.com/best-ad-blo...one-ipad-2019/