i need more storage on my macbook pro

Storage can not be changed after the computer is manufactured.

You can follow these instructions to free up storage: https://support.apple.com/en-us/HT206996

You can use an external drive and move data to it in order to free up space on your internal drive.

The only way is to purchase a another Mac w/more storage.

To live with existing storage you can store some stuff in iCloud. See that topic here:

Free up storage space on your Mac - Apple Support

Get and use a small. external drive, SSD is smaller than rotating, and use that for storing some items.

Most probably the Internal Drive is soldered to the LogicBoard and there is not was to replace the drive - period.

What is “Other” storage on a Mac, and how can I clean it out?

Free up storage space on your Mac

OmniDiskSweeper Safe to use

GrandPerspective 

How to delete Time Machine snapshots on your Mac

See used and available storage space on your Mac

The final word from Apple on Managing the " Other " Category

Other: Contains files that don’t fall into the categories listed here. This category primarily includes files and data used by the system, such as log files, caches, VM files, and other runtime system resources. Also included are temporary files, fonts, app support files, and plug-ins. You can't manage the contents of this category. The contents are managed by macOS, and the category varies in size depending on the current state of your Mac.