First thing, make sure your phone can actually use a card of that storage size. Phones have limits, so I would check the specs for that phone.
You can't use two cards set up as "Internal" the phone will only allow for one. So first you would have to take all files (not apps) off the card and place them either in a google or cloud account, or on a computer. Then you would have to move any apps that are on the card back to the phone's true "Internal" storage. Once that is done, and the card is empty you will need to format the card to work in any other device.
NOTE: You may want to consider not actually 'moving' any apps. Unless they have data that is stored in the app itself, it would be wise to just install them directly to the new card. Otherwise, when you move them to the phone and then back to the card, it can cause issues when getting updates for the apps.
Then, to use the new SD card, you will have to go through the same process you went through originally to change the card to "Internal" rather than "External" storage. Once it is done you can then move the apps back over to the card and the files as well.