Giant Touched (5e Feat)
From D&D Wiki
You've been blessed by magic granted by the giants, granting you the following benefits:
Increase your Constitution by 1, to a maximum of 20. You learn the Enlarge/Reduce spell and one 1st-level spell of your choice. The 1st level spell must come from the evocation or transmutation school of magic. You can cast each of these spells once without expending a spell slot. Once you cast either of these spells in this way, you can't cast that spell in this way again until you finish a long rest. You can also cast these spells using spell slots of the appropriate level. Constitution is your spellcasting ability for these spells.