It's not a straight forward process based on my experience (im not a highly technical user and not a dev). I haven't seen any DEX offering to swap tokens to MOnero given that most DEXs are not on Monero chain. And many CEXs are also not offering Monero due to regulatory issue. There are some CEXs you can use such as MEXC and TraderOgre using USDT and BTC as XMR's pair. I'm not aware that you will be flagged for buying XMR in huge quantity..which platform would flag that if you dont mind me asking.