It took less than 2 years to release BG2 after BG1. In the meantime Bioware licensed Infinity Engine to Black Isle who released Planescape Torment and Icewind Dale one year apart.
It took Larian 6 years to develop BG3 after Divinity 2. They moved on to their new game but that engine and assets could be similarily licensed to other studios to churn out some games using similar or simplified formula.
Definitely is. Try playing Divinity 2 and you will realize it’s the exact same engine just with a modified ruleset to match Baldurs gate more. I actually prefer Divinity, they just have more freedom as far as setting and the ruleset than a liscensed ip owned by another company