You can cast any spell as a Ritual if that spell has the Ritual tag and the spell is in your spellbook. You needn't have the spell prepared, but you must read from the book to cast a spell in this way.
Ritual Adept
Raw data
{
"name": "Ritual Adept",
"page": 155,
"level": 1,
"srd52": true,
"__prop": "classFeature",
"source": "XPHB",
"entries": [
"You can cast any spell as a {@variantrule Ritual|XPHB} if that spell has the {@variantrule Ritual|XPHB} tag and the spell is in your spellbook. You needn't have the spell prepared, but you must read from the book to cast a spell in this way."
],
"className": "Wizard",
"classSource": "XPHB",
"basicRules2024": true
}