Many races work well for Wizards, particularly sinceTasha's Cauldron of Everythingallows for greater freedom in assigning Ability Score bonuses from the start. The real trick in picking the right race is to make sure they have the fullest range of abilities that are actually useful to a Wizard...
You can hire lots of archers to repeatedly fire arrows at the dragon during the battle, which means they will rack up damage for all the high numbers they roll. You just need to make sure to use magic to protect them from the dragon's natural fear ability and buff them with spells or...