Number of trusted Apple ID

Hi! Could you pls help me

so I am currently attempting to sign into my other iCloud account. I recently got a new phone and I want to replace that number with my new number. My iPad is telling me I need to sign into my iCloud with my password which I already did, but then I cannot get in because it is saying that it sent a number to my old phone which I lost. I am unsure what to do

thank you