LTM device group - device certificate renewal

i have 2 LTMs in a device group and need to upgrade the certificates to a 2048 key.

i think key is already 2048, isn't it?

can someone advise of the best process - some articles mention remove the device trust?

i believe so.

can I just renew on each device and the certificate will update on the other device automatically?

i do not think so because you break the trust.