Beneficiaries (your children) do not "inherit" anything from trusts. Rather, trusts (typically) make distributions of assets, income, gain, etc.
If the trust distributes the actual shares to your children, then they will take those shares at a stepped up basis (at the date of death of the grantor). When they sell the shares, gain (if any) will be taxed at the long-term capital gains tax rate which is capped (currently) at 20%.
If the trust sells the shares, pays the tax on any gain, and later distributes the cash to your children, that distribution would be tax-free. If the trust does not pay the tax due on the gain but, instead, distributes the gain on their K-1s, then they would report the gain on their individual income tax returns.
