The $500 GeForce RTX 3070 provides 3440x1440 ultrawide performance roughly on a par with last generation's $1,200 RTX 2080 Ti, but don't discount memory differences.
RTX 3090 benchmark with Core i9-10900K 1080p, 1440p, Ultrawide, 4K benchmarks at Ultra Quality - GPUCheck United States / USA
AOC CU34G2X 34 Curved Frameless Immersive Gaming Monitor, UltraWide QHD 3440x1440, VA Panel, 1ms 144Hz Adaptive-Sync, Height Adjustable, 3-Yr Zero Dead Pixels, Black/Red : Electronics
Nvidia GeForce RTX 3060 Ti: 3440x1440 ultrawide benchmarks
MW2 Beta, RTX 3070, 5600X, Ultrawide (3440 x 1440)
3070 for ultrawide 1440p 144hz or 16:9 1440p 240hz? : r/nvidia
NVIDIA GeForce RTX 3070 Ti Gaming Performance At 4K & Ultrawide – Techgage
Destiny 2 (2020) Benchmark Using Nvidia's New Overlay, RTX 2080 ti, i9 9900k
Pairing a 4090 with an 8700k for 3440x1440 ultrawide gaming? : r/nvidia
Low FPS on ultrawide? : r/BaldursGate3
GeForce & Radeon Ultrawide & 4K Gaming Performance Roundup – Techgage
RTX 3070 vs RTX 3080 vs RTX 2080 Ti Ultrawide 1440p Benchmarks - Which GPU to buy for 3440 x 1440?