How do I reduce opt-outs when building a B2B email list?

Our B2B database is over 30K implied users.  Since COVID, I have noticed that there are more opt-outs per email send.  I think this is because getting in front of customers had become increasingly difficult and email was a strongly used method of communication. 

Granted our opt-out rate is still under 1%, but 1% of 30K is still quite a lot of missing contacts.  I do send messages to segmented databases so that the message is tailored for the intended audience.

I'm thinking it is time to start an official opt-in program.  Are there any best practices that can be shared for a database this large?

Many thanks!