Does giving charity for the sake of Allah Almighty after surviving an accident count as a ransom for oneself, and what is the correct intention for donating, and is there a specific amount for that?

Praise be to Allah, who saved you from what befell you. There is no specific expiation for what happened to you. Rather, you should strive to show gratitude to Allah Almighty by exerting yourself in His obedience and sincerely worshipping Him. Thus, adhere to the obligatory duties and increase in supererogatory acts. If you were to give charity as a form of gratitude, that would be good. There is no specific amount for charity; rather, you should perform acts of obedience and give charity as Allah facilitates for you, in gratitude for His blessings. A Muslim should be obedient and grateful to Allah in all circumstances, and gratitude should not be confined only to times when calamities are averted.