RTP is the game’s theoretical average return over a very large number of plays;...
https://www.quantifiedstrategies.com/rtp-variance-and-expected-value-applying-a-quantitative-framework-to-online-casino-gaming/
RTP is the game’s theoretical average return over a very large number of plays; the house edge is the share it expects to keep. A 96% RTP means a 4% house edge, not a promise that you’ll get 96p back from every £1 you stake