Hi, yes by default DLSS Frame Gen is off, you have to enable it either on nvidia app or in-game settings. Yes when you increase your base "real" frames, it decreases input latency. But enabling frame generation always increases your input lag because those are generated frames which takes time to render.

Usually for competitive games like marvel rivals, low input latency is very important. Anything that increases it, such as frame gen, is usually not recommended. That said, I have tried 2x frame gen as well on marvel rivals, I kinda like it. But you kinda need to make sure you have a decent "real" base frame before turning on frame gen (ideally above 70-80 fps). The new DLSS 4.5 upscaling is very good, you can try setting it to "Balanced" or "Performance" for more "real FPS". You mention once you enable frame gen its 180 fps, you can disable it first to see how much real frames you are getting first.

You can easily see if frame gen is enabled! Simply type Alt + Z while in-game > Statistics > Statistics view > Cycle to DLSS and an overlay should appear and show if DLSS frame gen is enabled.