Intro Shader like Summer Afternoon

how to create intro shader like summer afternoon website (
Please help me to create that shader

You mean the effect that transitions from the loading screen to the game?

One of solutions: add plane opposite camera. Add custom shader to plane with swirl and distortion. Make swirl with alpha. Every frame increase swirl scale and distorion.
Second good effect is “dissolve”

Yes that effect

There is a example regarding transitions

That’s how you can implement transitions, if you want the specific you can open a job post or if you know shader make it yourself using a basic shadertoy swirl/spiral in combination with simplex noise.