In one of the issues on the Gaming Bench YouTube channel, they showed how RX 6600 and RX 9060 XT show themselves in 1080r and 1440 rubles.
The test stand included the Gigabyte Z790 Gaming X AX DDR5, the Intel Core i5 12400F processor, the G.Skill Trident Z5 2x16GB DDR5 6000MHZ, ASUS Dual RX 6600 8GB GDDR6 and ASROCK RX RX RX 9060 XT 16GB GDDR6 Challenger Edition, SSD Samsung 500GB, Build Case Thermaltake N26, Windows 10 – Version 22H2 operational system, XPG S40G 512GB M.2, XPG Pylon power supply unit XPG Pylon 650W 80 Plus Bronze.
The game Silent Hill 2 launched with an preset Medium. The average frequency of personnel in it in 1080r was 40 films (6600) and 76 f/s (9060 ht), in 1440 rubles – 27 and 48 c/s, respectively.
Alan Wake 2 was tested at the Low graphics settings. On average, it was possible to get here in 1080r 38 f/s (6600) and 74 f/s (9060 ht), in 1440r – 25 and 53 f/s, respectively.
Forza Horizon 5 went with Ultra graphics. The average productivity in it in Full HD was 104 to/s (6600) and 213 to/s (9060 ht).
In the Horizon Forbidden West game, the average FPS was in 1080 rubles in the area of 45 fps (6600) and 88 fps (9060 ht), in 1440 rubles – at 25 c/s and 67 fans.
The game Spider Man 2 was tested with preset Medium. In 1080p, in it the average frequency of personnel was 58 c/s (6600) and 137 f/s (9060 ht).

You can familiarize yourself with all test results below the video.
Conclusion
Without taking into account the results with RT and FSR, the difference between the RX 6600 and RX 9060 XT was in 1080r – 90% (in terms of the average fps; 59 c/s and 112 c/s, respectively), in 1440 rubles – 112% (34 c/s and 72 fps, respectively).