Some estate attorneys think everyone needs a revocable living trust (RLT). Not everyone does.
Some estate attorneys offer to transfer assets from you into the RLT as part of their services. Partly for the fee income, but also partly because some people may not want to do it, may forget or delay, or may not do it correctly.
In order to transfer those assets into the RLT, they would need the asset information, including the account number. They would also probably need a limited power of attorney - authorization to act on your behalf for a specific purpose - to do the transfers.
If you decide you don't need an RLT, then the attorney has absolutely no need for your asset location, amount, or account number AFAIK. It also should be cheaper/faster/easier to prepare your will without the RLT language in it.
If the attorney is asking about the total amount of your assets, they probably are not trying to charge you more based on assets. They are probably trying to tailor their estate planning advice. You may not be close to the basic exclusion amount (BEA) now, but there are other things in play. Perhaps you are younger now and with compounding and income and SS and anything you might inherit, plus the fact that the BEA is getting cut in half on 1/1/2026, you might be over it later.
Even below the BEA, there are tax considerations, such as if you did choose to leave all of your assets to one person and most of it was in an IRA, they might have tax consequences related to the 10 year SECURE Act distribution window. There may be others.
If you're leaving everything to charity, your will in my state could be about three pages long, including the signature/witness page.
If you want to make things easier on your executors, make sure they understand your wishes, know where your accounts are located, and consider whether and how much you want to pay them. I don't have any executor pay in my will, but I do state that I want them to reimburse themselves for any out-of-pocket costs related to the settlement of my estate. Maybe your executor needs to fly to your state, stay in a hotel for a few days, and pay for some estate paperwork or tax prep stuff, that sort of thing.
If you want to, you can also leave that area of the intake form blank, meet the first time with the attorney, and ask them directly why they need it. That might cost you a bit more because you're adding a time-consuming bump in the road, but the cost might be worth your peace of mind.