Okay, so, my favorite and often times go-to shopping place is Ross's. They're relatively cheap and have a lot of cute and fun tops, such as polo, more "dressy" shirts, blouses, and everything else. If you can't find anything at Ross's, or you don't have one near you, Amazon has some pretty decent stuff for plus sized women. My favorites from Amazon are plus-sized polo tee-shirts since they can be used in a semi-formal setting.
https://www.amazon.com/Riders-Lee-Indigo-Womens-Tasting/dp/B08G8XKN1B/ref=sr_1_1_sspa?crid=LCWNKM00JW7A&dchild=1&keywords=plus+size+polo+shirts+for+women&qid=1605666101&sprefix=plus+size+po%2Caps%2C215&sr=8-1-spons&psc=1&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUEzUVNQVUhMRVBQUFEyJmVuY3J5cHRlZElkPUEwOTExMDUzNFZMN09JUjhCTEZXJmVuY3J5cHRlZEFkSWQ9QTA2Mjk2OTQzVVA4U0hTQlpDTTFRJndpZGdldE5hbWU9c3BfYXRmJmFjdGlvbj1jbGlja1JlZGlyZWN0JmRvTm90TG9nQ2xpY2s9dHJ1ZQ==
https://www.amazon.com/Woman-Within-Plus-Size-Perfect/dp/B008JHU9Y8/ref=sr_1_3?crid=LCWNKM00JW7A&dchild=1&keywords=plus+size+polo+shirts+for+women&qid=1605666101&sprefix=plus+size+po%2Caps%2C215&sr=8-3
https://www.amazon.com/Riders-Lee-Indigo-Plus-Size-Classic/dp/B012P2MR24/ref=sr_1_6?crid=LCWNKM00JW7A&dchild=1&keywords=plus+size+polo+shirts+for+women&qid=1605666101&sprefix=plus+size+po%2Caps%2C215&sr=8-6