How can we tell if a substitution reaction will be thermodynamically favoured

My understadning was like in the case of a cyclohexane we would see a thermodynamically favoured reaction if an axial substituent became equitorial in the case of a inverted Sn2 reaction but I would still like to know if there is a specific way to knowing if a substitution (Sn1 or Sn2) is favoured or if they are all favoured. I also know that E1 and E2 are entropically favoured and so they would be favoured thermodynamically under hot conditions, is this the dependant factor for Sn2/Sn1 as well? Any help would be immense thanks!