This visa form falls under the UK settlement route
This visa type allows these types of settlement applications:
Children under the age of 18 of a parent, parents or a relative present and settled in the UK
Adopted child under the age of 18 of a parent or parents present and settled in the UK or Child aged over 18 of persons present and settled in the UK Biometric immigration document (Biometric Residence Permit)
CHILDREN AGED 18 AND OVER
If the child entered the under 18 years of aged, these applications can be more complex because the child may no longer live at home, be self-sufficient
as they have a job or started their own family etc. Thousands of adult children have had their applications rejected.
Depending which visa you currently hold, will determine what evidence you need to submit to UKVI