select
    t0.*,
    t2.id two_years_later_id, t2.date_start two_years_later_date
from t t0
left join t t2 on t2.date_start = dateadd(year, 2, t0.date_start)
--where t2.id is not null -- Uncomment if you are only interested the matching dates
;

See the results in a fiddle.