It may prove advantageous to sell some of those appreciated assets in 2021 if the law change increasing capital gains to ordinary income tax rates only takes effect in 2022. When evaluating the guesstimated cost/benefits of selling now versus waiting also consider possible state income tax costs and planning.
It may be advantageous to shift assets into an intentionally non-grantor (“ING”) trust in a trust friendly (i.e., no tax) jurisdiction so that state income tax can be deferred or avoided. You might for example, provide in such a non-grantor trust that distributions can only be made to a spouse with the consent of an adverse party. That mechanism may permit a spouse to benefit from trust assets, not undermine characterization as a non-grantor trust, and still permit avoiding state income tax on a large sale to avoid an increase in the capital gains tax.
Note that in Rev Proc. 2021-3 the IRS will no longer rule on ING trusts so caution is in order. A non-grantor trust can be structured as a completed gift or incomplete gift. You can transfer assets to an incomplete gift trust if you have used all exemption, and still create a structure to avoid the state income tax on the sale. If you have exemption remaining that you want to try to use you can structure the non-grantor trust as a completed gift. Lots of options, but keep in mind the uncertainty, risk of retractive change, etc.