Go to the data folder of your old phone. Go to the Stardew Valley one it should have the stardew icon on it. Go into the folder and there should be a folder with your farm name. Grab that folder and upload it to Google Drive. Use the same account for Google Drive on your new phone and then download that save. Put the save back into the stardew folder on the data section of your new phone. That should work. Let me know if you have any issues.