Olivia Rodrigo feels excited for “all the good times ahead” after turning 21. The ‘Good 4 U’ hitmaker turned 21 on Tuesday (20.02.24) and Olivia has taken to social media to celebrate her landmark birthday. Alongside some behind-the-scenes photos of her birthday celebrations, the brunette beauty wrote on Instagram: “21!!! so grateful for all of the incredible things I’ve been able to experience so far and so excited for all the good times ahead [heart emojis] thx 4 all the love [kiss emoji] (sic)” Prior to that, Olivia revealed that she was celebrating her final day of “hypothetically” underag…