Can I combine projects into one invoice

Why not just create a project space for invoicing only? For example, you could call it {CLIENT’S NAME} 2024 Invoices. 

And if you haven’t already, check out the client workspace. You’ll be able to see all the client’s projects, invoices and communication in one place.

Love Regina's idea! If you already have the amounts on different files and need to combine them, use the copy block feature. 

Choose one to be your final consolidated invoice.

Open a 2nd tab with the other invoice.

In the services block, click on the 3 dots and choose "copy block"

Go to the final invoice and hit "paste block"

Repeat for as many services or invoices that need to be combined. 

Then delete the extraneous invoices.

Good luck!