A stock Ender 3 and TPU is going to be a challenge. Even if it you got it going you’d have to watch it like a hawk as it could jam at any time.
About the only way I could get my Ender 3 to print TPU consistently was to install a SeeMeCNC EZR extruder. Switching out the stock bowden tube with a Capricorn replacement helps too. Up to you if that would make financial sense given you may not print TPU very often.