I assume you mean that you do a
and want that to be done at every system startup. Then you could put it somewhere in the
script. A good place may be somewhere at the end. In RedHat 8 there is a comment that goes like this:
# Now that we have all of our basic modules loaded and the kernel going,
# let's dump the syslog ring somewhere so we can find it later
(It's quite close to the end of the file.) You could put your modprobe commands just before that.