Call to undefined method Maatwebsite\Excel\Excel::load()

Version 3.0 of that package doesn't handle imports yet. Release date for this feature is unknown. See this post for more details: https://medium.com/@maatwebsite/laravel-excel-lessons-learned-7fee2812551

I suggest you switch to version 2.*.

Else you want to continue further ALL Laravel Excel 2.* methods are deprecated and will not be able to use in 3.0 .

   Excel::load() is removed and replaced by Excel::import($yourImport)
    Excel::create() is removed and replaced by Excel::download/Excel::store($yourExport)
    Excel::create()->string('xlsx') is removed an replaced by Excel::raw($yourExport, Excel::XLSX)

3.0 provides no convenience methods for styling, you are encouraged to use PhpSpreadsheets native methods.

ALL Laravel Excel 2.* methods are deprecated and will not be able to use in 3.0 .

Excel::load() is removed and replaced by Excel::import($yourImport)
Excel::create() is removed and replaced by Excel::download/Excel::store($yourExport)
Excel::create()->string('xlsx') is removed an replaced by Excel::raw($yourExport, Excel::XLSX)

3.0 provides no convenience methods for styling, you are encouraged to use PhpSpreadsheets native methods.