It's useful to ask the question whether a modern army could beat a historical one on this or that level.
Some of the few authors on military affairs of the Renaissance doubted that their contemporary troops were the equals of Caesar's legions. This was in fashion, since the Europen Renaissance was about rediscovering the achievements of the antique Roman-Greek world, and using it as an example.
Later, doubts were raised whether the drilled and msuket-armed European armies of the Enligthenment era were at least the qualitative equals of the English longbowmen armies of the Hundred YearsWar.
These and other examples show how such a question can help to spot room for improvement.
A suitable reference for a modern army would be the German army of summer of 1941 (when at least its best third of divisions were at a qualitaty peak).
A simple question about whether the Bundeswehr's Heer could beat the Wehrmacht's Heer of 1941 would be trivial, since the quantitative ratio would prevent any battle. A more useful comparison would be for example the comparison between two infantry platoons or companies.
Potentially useful or not, most people would not gain much from such a thought exercise because apparently the intuitive reaction is to look at the hardware. The rifles shoot quicker, there are more radios, hard body armour plates stop bulets etc..
One needs a less superficial knowledge of how things were done (and how they're done nowadays) to compare the really interesting things. How well are they digging, camouflaging, encouraging each other, communicating, making snap decisions, using concealment, controlling fires and conserving ammunition? What tactics were and are used inside woodland and buildings? Sleep discipline? Physical and psychological conditioning? Tricks of the trade, reliability of security, marksmanship training, eyesight, noise discipline ...? What did they do when comrades were wounded? What were or are their drills?
In the end, my guess would be that a '41 Infanteriezug would be about the equal of a modern Bundeswehr Jägerzug man for man, and superior to a modern Panzergrenadierzug without its vehicles - under one condition: It would need to know the nature of its opposing force. The historical (small) unit would almost certainly be defeated if it had to dicover the firepower of rifles, night vision technology and heavy body armour during the fight itself.
Many small things would favour the historical counterpart, especially on the morale level but also by them being less overladen and thus more agile and able to exploit microterrain for survival.