Just chat it over with the solicitor you'll be using to draft the will. This is bread and butter daily work to them so tell them want you want and ask them about IHT and they'll draft the will accordingly. There are "copy and paste" clauses they use with the right "legalise" to deal with homes both for passing on to the next generation and dealing with IHT if relevant and looking after minor children.
But usually, if there is a major IHT change, like any other change in circumstances, the normal advice is to change your will or add a codicil. You can't prepare for every potential change in IHT or life events.
I think most homeowners would have changed their wills when the (new) residential nil rate band came into force as before then their wills would usually specify that their estate up to the IHT threshold would go to x and the remainder would go to y - or they'd set up some kind of discretionary trust, but with the new residential nil rate band, that clause became redundant for most homeowners with "average" value homes and estates, and in some cases, continuing having a will with that clause would actually mean more IHT payable than if the clause was removed. So solicitors were very busy for a couple of years rewriting wills and removing the clause!
When I look at probate records, wills, etc., (which is something I do quite a lot of), it's very telling that the vast majority of people's wills are within, say, 5-10 years ahead of them dying. Very, very few are "old" wills, i.e. 10+ years ahead. The general advice is to review every five years, and make changes if appropriate. You really can't make it once and forget about it as so much changes. Not only in terms of IHT, but also that if you have kids, your will will be very different whilst they're minors and will almost certainly need changing once they're adults. Likewise any bequests you make to people, your close family, partners, etc - if they die, then that's another trigger point for reviewing and replacing your will (or at least a codicil). Likewise when you get grandchildren, or your parents die, etc - you need to keep aware of who you've left money to, who you've nominated to look after your minor children, who's the next of kin if no will, who is the "residual" beneficiary if people you've left bequests to have died - so many factors and scenarios. Likewise appointing executors - sometimes you change your mind, sometimes your appointed executors die or become too old to do the job, and again, whilst you may want someone external be executor whilst your children are minors, once they become adults, you'd probably want to change the will to appoint them as executors instead. (They can still engage a professional to help but they'd be in control!).
Hence the general advice to review and replace every five years.
I think we've changed ours maybe 5-6 times over the life of our son who is now 23 and our current will is completely different to the ones we made when he was born! Some changes were due to IHT changes, some changes as he went through different ages and stages of life, and some changes arose due to family deaths or illness (people we'd originally nominated to look after our son if we both died, including guardianship but also financial provisions, i.e. a trust to cover living and education costs until he became an adult).
An old/out of date will is often worse than no will at all! And having no will is pretty bad! Don't "draft" it yourself - create a page of your wishes with various "what if" scenarios, and let the solicitor draft it.