Most of us file taxes electronically without any need for paper forms. However, paper forms are allowed in most cases and may be useful. Here are three downloadable and printable IRS forms from cpapracticeadvisor that may be useful now:
2019 Form 1040 for individual income tax filing
2019 Form W2 for reporting wages paid
2020 Form W4 for calculating wage tax withholding
Each form has instructions available online.
These forms are meant for public use, not for clients. Clients can use machine-generated forms where the data is generated though another program and automatically fills in the form.