In a duel 1 on 1 given equal skill of both pilots the X-Wings only Chance is to destroy a TIE ins head on attack. If the TIE manages to evade this initial barrage it‘s superior manoeuvrability and acceleration/deceleration mean there is basically nothing the X-Wing can do to shake it.
Think of it as wildcat vs zero without any gravity induced diving advantage to be exploited.
When fighting in groups it‘s a different story - working together the higher suvivability of the X-Wing comes into play. While a TIE is busy killing of the shields of his opponent a rebel wingman might take a shot on him.
So the X-Wing isn’t mainly designed to be the superior dogfighter - it’s designed to survive opposition and bring back the Pilot alive. As a defensive ship in prolonged close combat with Imp fighters the X-Wing performs moderate at best. As an offensive ship jumping in on a hit and run strike, delivering it’s payload and surviving long enough to jump out again - that is how the X-Wing was meant to be used. Quite fitting as the rebel alliance lacked a steady supply of recruits or ships anywhere near the empire. So trying to fight it out with the Imps in a battle of attrition would be a strategy for failure.
So why do X-Wings win in Lore often even their duels? Pilot quality. TIE pilots are well trained but most of their career means uneventful patrolling or at best fighting some second grade petty criminals. Alliance pilots surviving their first mission will have faced highly trained TIE pilots. And the X-Wings survivability means unlike their opponents they have a chance to learn from their mistakes. And even green pilots will fly wingman to a vet. So rebel fighter formations tend to be have vastly more combat experience then their foes.
Battle hardened TIE wings like the 181st or 204th tend to be serious trouble for rebel/NR fighters.
