After a certain update, contrails appeared for fighter aircraft at high altitudes, which is quite realistic, but also reduces combat effectiveness at altitude (easier to be spotted). However, in several battles, especially WWII rooms, I noticed some players’ aircraft did not produce these contrails. I remember in the game IL-2, adjusting the fuel mixture ratio can achieve this effect, but here I haven’t been able to try it out. Is there another method?
IRL contrails form as a result of atmospheric conditions - ther is nothing much can be done about that except fly at a different altitude.
Changing the mixture or other engine controls would make little or no difference.
Basically hte atmosphere has to be pretty much already saturated with ice and/or water vapour, and hte extra H2O frm the engine then pushes it above hte saturation point locally - which can also result in spreading contrails if the air is actually above saturation - “supersaturated”
This generally happens only at very cold temperatures - and therefore high altitudes (although it can happen at any altitude if it is cold enough and saturated enough)
The WT implementation of it is complete nonsense as far a I’ve noticed, with contrails forming at low altitudes in apparently fine/clear/warm weather.
The “hew” contrails were discussed quite often in the old forum.
Some bug reports like this:
https://community.gaijin.net/issues/p/warthunder/i/QeaGfZLGMnzR
are dealing with altitude issues.
Based on your question - yes you can avoid contrails - just turn your engine off. Depending on your plane you can glide very long distances and can dive from behind and above on some guys. Set prop pitch to 0% to reduce drag.