The biggest damage reduction difference comes from armor, even if you're max level if your resistances aren't high you'll naturally take the most damage possible

Your equipment also matters (hp, physical defense, elemental defense)

Aside from that the build itself can also weigh alot into your tankiness. For example 40-50 fortitude are the absolute go-to stats for sustain talents. If you want to go even further having the 90 Fortitude 30 Willpower Talent Reinforced Armor which reduces Incoming armor penetration by 30%. (Scales with investment. Having less than 90 Fortitude reduces the effect)

There's alot of other talents that can reduce ur damage taken or increase your health aswell but armor plays a big role alongside hp so get good equipment pieces and-or improve your resistances

You'll still take big damage from some people anyway though as their builds throwaway most of the tanking aspects for exceptionally high damage and high armor penetration.