Hello 6746,
It sounds like you want to add more than one album to a folder in the Photos app on your iPhone. If we understand what you hope to accomplish correctly, you should be able to with the steps from this article: Edit and organize albums on iPhone - Apple Support
Organize albums in folders
1. Tap Albums, then tap +.
2. Choose New Folder.
3. Name the folder, then tap Save.
4. Open the folder, tap Edit, then tap + to create a new album or folder inside the folder.
One you are at the step to create a new album inside of the folder, you can title it 'Holiday'. Then, you'll have the option to add the photos you want, or tap on the Albums tab to add your already created albums. Reply back if you get stuck or have any other questions.
Take care.