Hi Nakul,
Thank you for the answers,
In question #2, I have tried the second option mentioned in your answer, but I cannot get the offline option in the settings of my web map (figure below). Just for clarity, I created my web map by directly adding the layers in Map Viewer and then launched it, I am not sure if there is an error in my web map.
regarding question #1, I mean the layers within a single web map. I have flood hazard area layers for different return periods and I want that it shows me one layer initially and based on the need the rest of layers will be enabled by users.
Thank you,
Sefat