how do I have faith that my prayer will be answered in this specific way and not a general “whatever happens, His Will will be done?
You can’t be certain it will be that exact way, unless you are positive your prayer is the exact Will of God. Believe what you pray for you have already received. Because (Mark 11:24) says “Therefore I tell you, whatever you ask for in prayer, believe that you have received it, and it will be yours.“
See, even here, our part is to believe, our faith is crucial in life and in prayer. Now God can do whatever He wants. We must want His Will over ours, if they differ.
But it is not about our prayers being answered how we want. If humans got all we wanted, the world would be utter disaster. I understand your will for Covid-19 to end may be a seemingly good thing, but God alone is good (Mark 10:18) and all He does is better than anything that contrasts with His Will. If you ask His Will be done, and if His Will is done, then the best possible thing will be done. And is that not what we want? We certainly would rather the actual best thing be done than what we
think is best. And no one can fathom the mind of God (Romans 11:24) but He gives us the gift of faith (Ephesians 2:8) to trust Him through everything.
As for Elijah: We do not know every detail. Maybe He felt the Holy Spirit tell him to do what he did. Maybe God told him He would do it. Most probably, Elijah knew that if God did not send the fire, it would weaken the people’s faith in Him and endanger them. It is a great example of faith. It is not our job to worry about what God will do. We must simply set up every opportunity for Him to shine and glorify Himself through us and opportunities created. God used Elijah created an opportunity for His might and power to be made known. God may want to test the faith of His people with Covid-19, or He may want to bring home some of His people to Heaven, or He may want to bring people’s hearts together as we fight this together, or He may want to send society a wake-up call, or this may be the start of the end times. We could not possibly know at the moment, our job is to trust God.
Also, the gift of faith is one of the gifts of the Spirit. And the Spirit distributed different gifts to different individuals, according to the Will of God. So though all believers have faith, some may be granted more than others. With what we have, we must kindle and protect and never lose hope.
1 Corinthians 12:8-11
“To one there is given through the Spirit a message of wisdom, to another a message of knowledgeby means of the same Spirit,
to another faith by the same Spirit, to another gifts of healing by that one Spirit, to another miraculous powers, to another prophecy, to another distinguishing between spirits, to another speaking in different kinds of tongues, and to still another the interpretation of tongues.
All these are the work of one and the same Spirit, and he distributes them to each one, just as he determines.”
And Elijah lived before the outpouring of the Holy Spirit at Pentecost, but God could still fill certain people with the Holy Spirit at certain times.