I have check several sites like Bitvest, Stake, Duelbits, Sicodice, Crypto games, and Bustadice, unfortunately the house edge of these sites is 1%. Crypto games was used to be 0.8% and they also have 0.4% house edge promotion for VIP members, but I'm not sure how about now.
I have not heard of this kind of promotion. Who can be a VIP member and which casino allows it?
But that's why I know about a completely different kind of promotion: the casino has an RTP on the Dice game of 99%, but if the welcome bonus is accepted then the RTP is 97%. And I noticed that before I made the deposit, so I gave up.