Standard Way to Enforce Regional STS endpoint

[haoboyuan-db]

As mentioned in title, i know that for previous v1 golang sdk, when we want to have regional STS endpoint, we can just use
awsConfig := aws.NewConfig().WithRegion(region).WithSTSRegionalEndpoint(endpoints.RegionalSTSEndpoint) and create any client we need using the config.
What is a standard way to do the same thing in v2? I see there is a client for sts now, do we use that? I know there is a same question asked in 2022 Oct, but that answer of finding the default value for v2 is regional now seems not correct, as I see from the webpage it is now default as "Default value is legacy."