I only hope Trump told Erodogan to not look for our help, or NATO’s help in any contest between him and Assad. Turkey is stronger on paper but Assad has Russian support if he needs it. Also, Erdogan is using a lot of hired help in Syria - former ISIS & Al Qeuda “refugees”, so Turkish families will have fewer body bags returning home. That hired help knows the landscape and has battle experience fighting Assad, and losing to Assad. They lose mostly because Assad knows he is outnumbered and employs a scorched earth policy as much as he can - simple, brutal and mass destruction where he finds his opposition is sitting. Tons of “collateral” civilian deaths and casualities, but effective to Assad’s purpose.
NATO is a defensive pact, and Turkey invaded Syria, so they can’t ask for help.
But there is no more collateral damage at all coming from Assad, then there is coming from Isis, and Assad is the legitimate government.