Yes you can turn either one off and use only one of the SIMs (eSIM or Physical SIM). Yes you can forward calls from the US SIM to the Mexico SIM however note that if the Mexico SIM has a number in Mexico then you may be charged for those with International rates. Double check with your service provider on this one before forwarding.
Now the issue comes with text forwarding because once you turn the US SIM off then that number will also disappear from Message settings (Send & Receive) so you won't be able to get those texts and messages.
My best bet recommendation is turn off the US SIM and go on with your Mexico SIM while in Mexico. Ensure that call forwarding from US to Mexico number will not cost you extra. If it does then do not call forward. Forget about Text forwarding. Enjoy Mexico.
Axel F.