I prepared a command that works and does its job correctly
powershell -Command "(gc copy.json) -replace 'field_type','field_name' -replace 'aaa','AAA' -replace 'Bbb','BBB' | Out-File copy12345.json"
But I would like each '-replace ...' to be on a new line for better readability. I tried the following solution and also brackets for the whole command, but it didn't help.
powershell -Command "(gc copy.json) ^
-replace 'field_type', 'field_name' ^
-replace 'aaa','AAA' ^
-replace 'Bbb','BBB' ^
| Out-File kopia12345.json"