Upload image and resize

Laravel 6

I have a few questions:

1. What is the best way to upload a photo using the form and save it, e.g. in /storage/app/public/files/users/user_id/image.jpg?

2. How to resize a photo and save its thumbnail, e.g. in /storage/app/public/files/users/user_id/image_thumbnail_150_150.jpg?

3. What functions built into laravel to use or external libraries?