If they are expenses for a JOB (you are an employee and will be issued a W-2 at the end of the year) you cannot claim those expenses. 

There was a time when that was possible, but now work related expenses are limited to only the Self-Employed. 

I bought all that for my real estate job/ self employed. I needed it to do online school but didn't receive my license and become active til Jan 2021. Now I'm wondering if I can just hold on to the receipts and claim it on next years taxes? Or just call it a loss?

When you started business activities is the business start year.  Purchasing equipment and supplies and getting training for licenses are start up business activities.  These are start up costs and normally you would have to capitalize (depreciate/amortize) these items over a year or more.  However, you can expense up to $5000 of start up costs in the first year.

You can have business expenses before having business income.  You will enter these expenses and assets in the "Self-employment" topic under the "Wages & Income" tab.