What can i do if i lost my iPhone where i had my apple watch log in and i don’t remember my old icloud

See this about Activation Lock on the Apple Watch. About Activation Lock on your Apple Watch - Apple Support

You will need to recover the Apple ID. You should have done that instead of creating a new one. Start here, If you forgot your Apple ID - Apple Support

How to pair your watch with a new phone

And start at the section "If you don't have your old iPhone or you erased it"