The 49ers are about to find out a lot about themselves the next two weeks.

The first three weeks haven’t quite been all sunshine and lollipops (except the ones they hand out at the doctor’s office), but it’s been pretty easy, breezy and beautiful all things considered.

Heck, last week was the first time they needed to use their starters for the entire fourth quarter.

Hopefully they enjoyed it while it lasted. The schedule takes a decidedly different turn with the Super Bowl hopeful Broncos visiting Levi’s Stadium this Sunday followed by the Niners’ first true road game against the defending Super Bowl champion Seahawks.

Coach Kyle Shanahan is aware of what’s in front of them.

“People [can] say I’m in a flow, so my wife will take it, pump me up,” Shanahan said. “[But] I know once you start saying that, I know what next week looks like [in Seattle].”

Before the 49ers kick off against the Broncos and things start to get real, let’s take a step back to examine what’s real from their 3-0 start, what’s a mirage and what is too soon to tell.

Claim: The 49ers’ offense is operating at its highest level yet.

Verdict: Real

Shanahan isn’t taking any victory laps yet. But nobody would blame him with how he has the 49ers’ offense humming. In Year 5 of their partnership, Shanahan and Brock Purdy have elevated an already potent attack into another stratosphere, and there’s evidence it can sustain.

A football researcher and X user looked at the past 16 NFL seasons and found that early offensive success is far more predictive of the future than on the other side of the ball.

Usually, Week 8 was about the point that teams began to separate themselves. Using the metric Expected Points Added per play, 74% of the teams in the top eight by then remained there at the end of the season. But the biggest week-to-week jump occurs from Week 3 to 4.

The Broncos have playmakers at all three levels of their defense, and they should provide the best measuring stick yet for the 49ers. But even if they lay a dud against Denver, their offense to date has been so dominant that they would still rank among the NFL’s most efficient.

Entering Week 4, there’s more separation between the Niners in the top spot of EPA/play (0.33) and the second-place Bills (0.22) than there is between Buffalo and the next six teams.

Claim: The offensive line is never going to give up a sack.

Verdict: Mirage

It hasn’t happened yet in three weeks, so it’s not entirely ridiculous to pose the question.

But, yes, the 49ers’ offensive line will eventually allow Purdy to touch the turf. It might even come this week against the best defense they will have faced and potentially the best single pass rusher in Zach Allen, given Myles Garrett’s limitations when they stifled him in Week 1.

That doesn’t mean the unit hasn’t emerged as a big part of why the offense has been so good.

Through three games, they rank first in Pro Football Focus’ pass-blocking efficiency metric.

“The hate on our O-line always surprises me, personally,” Shanahan said. “I love our O-line. I think they’ve been real consistent for a number of years, and they’re playing really well right now.”

Claim: The defensive line can withstand the attrition.

Verdict: Too soon to tell

Imagine where the 49ers would be if they hadn’t gone out and traded for Osa Odighizuwa this offseason? That was general manager John Lynch’s response to the pass rush’s shortcomings last season, and just three games into this year he’s the one holding it together by the seams.

In fact, the 49ers have already managed to rack up 28 pressures, more than a quarter of last season’s total, despite missing Nick Bosa and five other defensive linemen. However, not many of them came in the second half last week, when the undermanned group ran out of gas.

The unit in its current state probably isn’t sustainable, but it’s shown the potential to be a vast improvement from last season. They just have to get healthy.

Claim: Raheem Morris was a home run hire as defensive coordinator.

Verdict: Real

This much has been clear, despite yielding 30 points to the Cardinals last week.

Two of Morris’ best-known attributes when he was brought in to replace Robert Saleh were his background with defensive backs and his ability to design and disguise creative blitz packages.

That’s allowed the 49ers to more than tread water while they deal with injuries on the D-line.

Morris had the challenge of installing a new defense to a veteran group that had mostly played in the same system for years, but linebacker Fred Warner said he was “comfortable from Day 1.

“Just because of the type of coach Raheem is and the teacher that he is. … I’ve never gone into a Week 1 game as prepared as we were that game.”

Claim: Concerns about age and injuries were overhyped.

Verdict: Too soon to tell

It’s only Week 4, and the 49ers already could use a CliffsNotes version of their injury report.

But while other teams have been smoothing out the kinks on the field, the veteran-led 49ers have been operating like a finely tuned machine from the first snap of Week 1.

The 49ers began the season with a league-high 14 players age 30 or above on their 53-man roster, but just one — Demarcus Robinson — is among the 16 currently on injured reserve. If anything, their experience has worked in their favor early on this season.

To boot, George Kittle looks no worse for the wear after tearing his Achilles, Warner is back to normal after missing the final 12 weeks of last season and Bosa had been explosive in two games back from ACL repair before pulling his calf warming up for practice.

How those bodies hold up in December and January, well, that remains to be seen.