Assigning Moderator Role to One Specific User only

I am working with React SDK,

when a user joins the meeting at that time, we want to assign moderator role, and based on that we wish to so toolbox buttons like chat, mute, screen share, etc
For example, If the user is not a moderator, we don’t want them to share a screen,
How can we assign moderator role with conjunction with our backend API business logic,

Another question,

Also when the moderator leaves, the moderator role is assigned to the next participant.
How can we stop doing that?

This is the default behavior first one to join is the moderator and when it leaves at least one moderator needs to be in the meeting and a random one is chosen.
One option is to enable jwt tokens and tight them to your existing authentication and use something like:
prosody-plugins/token_affiliation at main · jitsi-contrib/prosody-plugins · GitHub to assign moderator based on a field in the token.