In brewing it is often a mistake to try to take one variable in isolation.
If everything else was the same (pH, temperature, water chemistry...) then yes thicker mashes favour the enzymes that give beer with more body. The effect of temperature is bigger so by mashing a little hotter you favour body, adjusting the pH up a bit to favour Alpha Amylase over Beta will also have an effect, to some extent more Calcium will protect Alpha amylase again favouring higher body.
On their own (except possibly temperature) each might not have a huge effect, in combination of all of the above can and will make a pronounced difference.
Its hard to say what is a "Typical" anything for BIAB brewers, the original or classis BIAB was an all in at the start so 5-6:1 L:G for most brews, all things being equal a condition that favours the classic pilsner type of beer body and flavours. The get into AG for $20 thing, can easily create great conditions for pretty gluey beer.
A bit of playing around with the strike water calculations shows that mashing in very heavy (<2.5:1) means that your strike water is so hot some brewers have had attenuation problems as they were killing of most of the beta amylase, guaranteeing lots of body.
A balance of all the factors and knowing a bit about how they interact will give you a lot more control of what you are brewing.
Mark