No. Lord Vishnu had determined the death of Ravana and his allies. Sita was merely the justification used to launch the campaign.
Lord Vishnu says to the devas
“O Devas, fear no more, peace be with you. For your sake, I will destroy Ravana, together with his sons, grandsons, counsellors, friends and relatives. Having slain that cruel and wicked asura, the cause of fear to the divine sages, I will rule in the world of mortals for eleven thousand years.”
- Sarga 15, Bala Kanda, Valmiki Ramayana.
Ravana through his years and years of sinful and wicked behaviour had sealed his fate.