That's impossible to know without knowing too much to yap on this forum. US/China would not build those platforms if stealth doesn't work.
My guess is that overflying hostile territory would still be very risky, even for an all-aspect broadband stealth aircraft like the B-21 or H-20
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But remember that for Chinese stealth bombers, there is no practical requirement to overfly hostile territory.
Beyond the 1IC, it is mostly:
1. empty ocean with some scattered islands and naval ships as targets
2. a few cities and bases along coastlines
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From the Chinese perspective, a H-20 will definitely work.
But we can't say the same for the B-21 trying to penetrate a dense, overlapping network of sensors in China.