No, earliest is age 14 for solo in a glider. They then have to wait until 16 to get a licence under the EU FCL rules.
In the UK the first solo age has been 16 until a few months ago but this was changed (by the BGA) to align with and anticipate the implementation of EU rules, which although in place legally are not in effect in practice yet in the UK.
Solo at 14 has been the case in Germany for a long time, with no particular adverse consequences
afaik.
Allowing someone to solo is entirely the discretion of the instructor, as it has always been.