Did Martin Luther realize posting his 95 theses could be a world-changing act? Did he want it to be?

Scholarship general agress on two points: (1) Luther wanted to change the Church, and thus the world (2) ...but not like that.

The history of the Church in the Middle Ages, you see, is the history of a Church in reformatio. We can talk about the Carolingian reforms of liturgy and monastic life (9th century), the Cluniac reform of some branches of monastic life (late 10th/early 11th), Cistercian monastic reform accompanied by a recentering of traditional and Cluniac (now Benedictine) life in the 12th century, the rise of lay-based religious movements reforming local church life later in the century that get condemned as heresy, the mendicant orders (Franciscans and Dominicans) in the 13th century as preaching orders to prevent more lay heresy, the beguines/penitents/anchoresses of the women's religious movement from the late 12th century that insist on women's rights before God and as Christians ministering to society, Observant reform in the mendicant orders from the late 14th century, the Devotio moderna in late 14th/early 15th centuries as another manifestation of reaching the laity, the reform of preaching and theology in the 15th century to shift popular Christianity into a "belief system" of principles that people learned and believed, the "heretical" Lollard and Hussite groups in the 14th/15th centuries that sought to change basic practices concerning the Eucharist and devotional prayers, et cetera et cetera. Thomas Brady had shown how, in addition to the theological/devotional reforms mentioned above, German nobles spent basically the entire 15th century reforming he local churches in their principalities along financial and political lines as the institutional Roman infrastructure repeatedly failed at it.

What all of these reforms had in common was that they were reforms. That is, they aimed to fix the existing Church, not start a new one. (Yes, even those stamped as heretical by anxious clergy). There is no reason to suspect Luther soughht anything more--or, frankly, anything less. I've talked previously on AskHistorians about how Luther intended the theses to be An Event (https://www.reddit.com/r/AskHistorians/comments/6ei41h/martin_luther_nailed_the_95_theses_to_the_church/). Howefer, it was an Event aimed primarily at Church prelates, not immediately at the laity. That happened very quickly, with the printing of the theses in German, but it was not how he started. Luther himself was even still showing up to the Leipzig Disputation and the Diet of Worms to defend himself before the Church hierarchy--in short, recognizing Rome's authority to call him to account, even if he had come to believe the Rome-based Church had gone far astray from what it ought to be.