Read data from 125kHz tag and write into 433MHz remote
In the comments you say that your garage door opener has a 433 MHz receiver, but you don't have the matching remote. Unfortunately without one it may be impossible to determine what protocol and codes it uses (probably a rolling code which is very different from an RFID tag).
However you could use your remote to send a signal to a separate receiver which then emulates the tag, placed close to the door reader. The wireless link could then use whatever protocol and codes you like (eg. a standard remote tx/rx set). The only question then is, can you 'clone' the tag?
Another option might be to tap into the 433 MHz receiver circuit inside the door controller, then use that signal to operate the door directly from inside the controller (bypassing the original decoder section). Or if that signal is not available, install a separate receiver and use its signal to operate the door control circuit.