Can Allah forgive the sin of someone who allowed a young man to see some of her body online, and she is now remorseful and repentant?

Fear of the consequences of sin is proof of faith. The believer sees his sins as a mountain above him, while the wicked sees them as a fly that passed over his nose. A believer should not despair of Allah's mercy, for Allah loves forgiveness. The Messenger of Allah, peace and blessings be upon him, said: "By Him in Whose Hand is my soul, if you were not to commit sins, Allah would do away with you, and would bring people who commit sins, and then ask Allah for forgiveness, and He would forgive them." In another hadith: "A servant committed a sin... so he said: 'My Lord, I have sinned... so forgive me.' His Lord said: 'Did My servant know that he has a Lord who forgives sins and takes one to account for them? I have forgiven My servant.'" So repent and seek forgiveness, have a good opinion of Allah Almighty, and be optimistic about His forgiveness.