This is misleading, I would request further elaboration if the thesis is clear. The concept of PE is to figure out valuation. This needs to be studied along with other factors. An industry may command a low PE (various reasons, low growth rates, low margins, high debt etc).
Bull markets due to high liquidity and tailwinds lead to PE expansion in many sectors. However, in bear markets, PE contraction may take place ( eg. a lot of renewable energy companies corrected from peaks recently).
Irrespective of market (bull/bear) - margin of safety should be looked at. Bear markets often provide better opportunities to find quality low P/E stocks, but valuation should always be assessed holistically.