Uhm, well no
A
lean to is a reference to an add-on attached structure which leans on an existing structure, hence the term lean to.
A stand alone (detached) structure can have one of many roof configurations on it. The flat sloping roof is the simplest and most economical. It is termed a
shed or
flat roof. It must have some pitch(slope) to shed the rain. If you are in snow country then anticipated wet snow load may dictate a steeper pitch. I hope this helps.
I put up a 10x10 shed in the yard with a regular 8ft wide roll up garage door. I used a gable roof and utilized the top section as additional storage.