There are varying degrees to this but I'll focus on the early stage, low effort approaches I've found work.
For an easy, slightly hacky version I've used git-crypt (https://github.com/AGWA/git-crypt) with tiny teams. You'll need to share the decryption key (e.g. via 1password shared vaults).
As your need for security grows (but you're still not working with a giant team) you're better off using non-committed .env files locally (with need-to-be-shared dev keys stored in shared vaults in 1password) and prod GCP/AWS secrets managers remotely.
Once you work with a bigger team you'll need to start minting API keys limited in scope to each individual, for them to work with locally. The prod keys will only live in the remote environment, managed by some kind of secret manager offered by the platform and will need to be rotated frequently.
For an easy, slightly hacky version I've used git-crypt (https://github.com/AGWA/git-crypt) with tiny teams. You'll need to share the decryption key (e.g. via 1password shared vaults).
As your need for security grows (but you're still not working with a giant team) you're better off using non-committed .env files locally (with need-to-be-shared dev keys stored in shared vaults in 1password) and prod GCP/AWS secrets managers remotely.
Once you work with a bigger team you'll need to start minting API keys limited in scope to each individual, for them to work with locally. The prod keys will only live in the remote environment, managed by some kind of secret manager offered by the platform and will need to be rotated frequently.