Noticed that I am only receiving one bar from my 4G LTE carrier in the past couple of months.

I have an Apple XS phone and until the last couple of months I have not had any problems with picking up my phone carrier's LTE signal when I am not using my wifi at home. I have contacted my phone carrier and was informed that with the XS I should not have a problem receiving 4G LTE signal since the phone is approximately 3.5 years old. I have attempted the recommendations that I have read on this forum such as turning off your phone, which I do regularly, resetting my network settings but I continue to experience the same poor connection issue. I am aware of concept of obsolescence but especially during these difficult economic times just buying a new phone is not really a viable option at this point. The only option I have not tried yet is taking out and re-installing the sim card. Are there any other troubleshooting options available? Thank you very much in advance.