How can I do it if I don’t have my old phone and I’m tryna set it up to my other phone but it’s on activation lock

You can still set up the new phone, you just will not have any of your information on it.

To regain access to your Apple ID, visit iforgot.apple.com

To remove activation lock, visit https://support.apple.com/en-us/HT201441

You can request an Online Activation Lock Removal HERE.

Or this;

If you can't remember/gain access to the apple id that paired the watch to the phone.Take the watch and it's receipt along with some photo id and any other proof of ownership to an Apple Store and request that they remove the Activation Lock for you.