When moving to a cloud model for your database stack no doubt you will be involved in a costing exercise. The good news is if you have Software Assurance with your existing licenses then expect some cost savings when moving to the cloud. You can save up to 70% cost when compared to a pay as you go model.
For Azure SQL Database the saving example is shown below. I was building a solution based on Business Critical SQL Database 12vCore Generation 5 and 1TB max data size.
Cost shown below:
Ok, so now if you have the ability to select Azure Hybrid Benefit, you will notice cost savings.
Very significant savings.
Now what you create in Azure with this license does depend on your on-prem license footprint. For example, if you have SQL Server Standard Edition core with SA and want to build Business Critical databases in Azure then with hybrid benefit this will map as 4 core on-premises to 1 core in Business Critical.
I suggest further reading here: https://docs.microsoft.com/en-us/azure/azure-sql/azure-hybrid-benefit?tabs=azure-powershell