Input Attenuation and Intermodulation Products
I guess your signal is a sum of 2 or more sinusoidal signals. You use that signal as an input for some circuit which is non-linear and causes intermodulation.
The general rule: The intermodulation products generally become stronger as the signal power increases
But that depends on the mathematical form of the nonlinearity. There are some well known theoretical special cases which do not obey the general rule.

The circuit is linear as long as the signal amplitude is under certain limit, a small power increase causes no intermodulation, it stays zero

The circuit has no linear range, it works like a comparator with treshold at 0V and the input has no DC. The output is the same rectangular pulses at any input level.

The circuit has a dead zone around zero like cross-over distortion in badly biased class B audio output stage. There's very heavy intermodulation distortion if the signal is weak, but it doesn't increase if the input signal level is increased. At levels high enough but still so low that no clipping is caused the apparent distortion can be neglible as percents.


Unfortunately we know nothing of your circuit so no actual analysis is possible.
The intermodulation distortion is used as measure of quality for many circuits. Does the circuit fulfill the spec is inspected by inputting  a certain test signal and by checking that certain intermodulation products are low enough.
Make a web search for intermodulation and intermodulation distortion measurements.