You could just pop on the filter plate so it has the filter built in.
Something like this
https://www.ebay.co.uk/itm/265019124632
You would only need to install the faceplate, not the back part.
It literally just pushes in, nice and easy.
Or you can replace the whole socket with a new one, mk5 version, but this would require touching the wires at the back of the master which is against the terms and conditions of openreach and would be at your own risk / not advised unless you know what you’re doing. That said it is only two wires A and B and it’s self terminating.
NTE5C MK2 + VDSL MK4 OpenReach Telephone Master Socket + Back Box
https://www.amazon.co.uk/dp/B07LFMPVX4/ref=cm_sw_r_c...
Again as a novice recommendation to just get the filtered socket part for the older box, if you want it to look neat, else using ISP filter is absolutely fine and won’t impact performance really.