Sending messages to iPhone with File attachment

I just switched phones and carrier, going from a Huawei P20 to a Samsung S20 FE 5G. I used to be able to easily send PDFs and other files via MMS (as long as the file didn't exceed a certain size). Since I changed phone/carrier, I am no longer able to send files to iPhone users. I still have the options to send files to other Android user, but that doesn't seem to be an option with iPhones, which is an absolute deal breaker for me as I rely on it quite a lot for work where everyone but me is using an iPhone. Do you know of a work around or way that would allow me to send PDF files via "text message" as I used to? And I of course mean actual files, not links to cloud drive. Thank you for your help!