Hi there, in my P1S with PEI plate and nothing else never and ever have had a warp problem.
My routine and settings:
pei textures and esun PLA+
bed temperature 60
noozle temp 220 for the firs layer then 215
50mms speed for the first layer
no fan until the 3rd layer after that 100% hotend and 50% aux Chamber always 0%
After say 15 prints depend on the size I will turn the plate and use the other part, after other 15 prints I will wash just with very warm water soap and steel wool 000, then wash very well until when make a noise under my finger ( I hope you understand, same noise when plates are clean and totally degreased) then I dry out with a special cloth for drink glasses.
I print a lot of very small parts and also large and log, like some pots and never had warping…