Hello,
For just assessment, a trained Psychologist can get the assessment done.
For assessment and treatment (medication), only psychiatrist can do.
Different scales are used for ADHD assessment.
Assuming that it is for child, parent rating scale can be done online.
Even for adult online assessment can be done.
But online assessment can have its own limitations.
Hence better to meet a psychiatrist in person
Next Steps
consult a psychiatrist, preferably child psychiatrist for child, for assessment and further management