When you jump into an online slot, the RTP tells you how much you can expect...

https://www.coast-bookmarks.win/when-you-play-online-slots-pay-attention-to-rtp-that-s-the-percentage-of

When you jump into an online slot, the RTP tells you how much you can expect back over time—usually around 95% to 98%. Volatility shows if wins come big and rare or small and steady