To get to the Volcano Manor without venturing too far into Elden Ring Runes Mt. Gelmir, there are two primary methods:
Via the Raya Lucaria Academy: After defeating Royal Knight Loretta in Caria Manor, you can explore the area around Liurnia of the Lakes and head toward the Raya Lucaria Academy. From here, you can cross into the Forbidden Lands to eventually access the Mt. Gelmir region. There are pathways that lead you to the manor entrance, though it's advisable to be cautious as this area contains tough enemies and hazardous terrain.
Via the Altus Plateau: If you've already reached the Altus Plateau, you'll be closer to the Volcano Manor entrance. Proceed to Mt. Gelmir using the Dectus Lift or the Grand Lift of Dectus after finding the required Elden Ring Items like the Medallion. This path, while easier in terms of accessibility, still brings its own set of challenges, including tougher monsters and hidden areas that require sharp navigation.
Either way, once you've made your way to the Volcano Manor, you'll be greeted by Tanith, the Lady of the manor, who will offer you a place in her house and introduce you to buy Elden Ring Runes the questline. From here, the journey officially begins.