Net profit margins have certainly gone up a lot in recent years, but that has now been going on so long that it mostly defines the new normal as far as my smoothing functions are concerned.

PS

Here's a chart from the Fed to get a feel of the change
St. Louis Fed (FRED): Corporate Profits After Tax (without IVA and CCAdj)/Gross Domestic Product | FRED
Note the typical figures up to 2004, compared to the typical figures 2005 and later.

A dollar of US company sales has been 63.3% more remunerative in the last 18 years than it was in the prior 50
Three main factors, I believe: Lower fraction of GDP going to labour, lower corporate taxes, lower interest costs.

It's not just that the business sector is now dominated by some very large wildly profitable businesses.
Perhaps surprisingly, overall US corporate ROE seems to have been lower in the last 5 years than the historical norm, not higher.
For non-financial firms: St. Louis Fed (FRED): Financial Soundness Indicator, Nonfinancial Corporations; Return on Equity (Percent), Level (BOGZ1FL010000296Q) | FRED
Average ROE last 18 years 9.89%, down from average 11.39% in the prior 30.
Average last 5 years only 8.21%

This isn't exactly intuitive--corporate leverage has gone up because of the long period of low interest rates, which you'd expect to boost ROE, no?
But in fact the leverage hasn't changed that much (net), in terms of debt:equity ratio.
Recent figures are around the middle of the trendless range in the last 25 years.
St. Louis Fed (FRED): Nonfinancial Corporate Business; Debt as a Percentage of Net Worth (Market Value), Level (NCBCMDPNWMV) | FRED

So, overall, it seems to take fewer sales but more equity to make a buck of net income.

Jim