Not as far as I know. What you could do is programmatically scan
through the SMS messages yourself using AT commands and delete the
oldest make to make space for the new.

regards
Marcus

I don't know of any "onboard" deletion mechanism that gets
triggered by the need to make room for a new MT SMS.

And as Marcus says, a standard approach is to regularly read any
"unread incoming" messages (which changes their status to "read
incoming").  And combine this with regular deleting of read
messages.  If the storage capacity of the modem/SIM gets
temporarily exceeded, the surplus messages just get buffered in
the SMSC of lodgement until there's room for delivery.

A different approach is to reroute incoming messages to the
serial port, so that they never get stored on the phone or SIM.
To achieve this, commands to look at include AT+CNMI, AT+CNMA,
AT+CPMS and AT+CSMS.  But I'd check the behaviour when the serial
port isn't available to take them, as you might find these get
delivered and stored rather than buffered in the SMSC (especially
if the modem gets reset).  And if so, this might require you to
implement "read from storage and then delete" logic in such cases
anyway.

John