You need the SSA-1099 to report the benefits received accurately. Unless you have changed your address then you should have received the form in January 2020 for tax year 2019.
Go to this Social Security Administration website for how obtain the form - https://www.ssa.gov/myaccount/replacement-SSA-1099.html
However, if the Social Security benefits are the Only income to be reported on the tax return, then there is no reason or need to file a tax return.
