The specifications are perfectly respectable for After Effects work, so you shouldn't have any major issues.
The GPU is certainly the low point of these specs, but this shouldn't be too much of an issue. Unless you are planning to use super complex GPU-driven effects, like complex 3D models in VCP Element, for example,
I'd hate to work full time on a 13" screen, so hopefully you have access to an external monitor when required.
I have a slightly older (8th gen) Core i5 model of that same Mac, with four USB/Thunderbolt ports. My After Effects projects are relatively simple and usually less than 30 seconds long, and my 13" MacBook Pro works fine for that. The limitations below may affect you differently depending on much your compositions use layers and effects, and how large their frame sizes are.
After Effects is extremely CPU-intensive, but cooling is very restricted on that thin MacBook Pro. If you have large frames (4K+), several layers, intensive effects, or anything else that would result in high CPU usage for extended periods of time, expect the MacBook Pro to operate at or near its maximum internal temperature, with the two cooling fans running hard and loud most of the time.
“Up to 4.1GHz Turbo Boost” means if the Intel CPU is asked to work its hardest, it will try for 4.1GHz, but it can maintain that Turbo Boost speed only as long as temperature allows. If the cooling system is maxed out, the CPU will reduce speed until temperature can be held within the safe maximum of that Intel CPU, which I think is 100 degrees C. That’s for the four-port model; the thermal limiting is even worse on the 13" MacBook Pro with only two USB/Thunderbolt ports because that model has only one fan.
The integrated graphics are a limitation, of course it will limit performance of any GPU-accelerated effects you apply, as well as final rendering/encoding. I also notice the graphics being used during RAM previewing. To give my 13" MacBook Pro a full discrete graphics card, when it’s at the desk I plug a Thunderbolt eGPU into it, driving a large external display. Because After Effects doesn’t use the GPU as thoroughly as Premiere Pro, overall I think the CPU+cooling limitations of the Intel 13" MacBook Pro hold it back as much or more than its graphics limitations.
The 16GB RAM will probably limit how long of a RAM Preview you can do. If you try to RAM Preview your entire timeline but After Effects will only do part of it, there probably isn’t enough free RAM. Quitting other applications can free more RAM for a longer RAM Preview, but if that still isn’t enough, then you have to start changing Preview options to skip frames or lower the resolution of the RAM Preview. If 32GB RAM had been an option when I bought my 13" MacBook Pro, I would have taken it.
The 1TB storage is a good capacity as long as you are not going to fill it up immediately. Fortunately, MacBook Pro internal storage is among the fastest available. If you plan to use After Effects when mobile, the internal MacBook Pro storage will have to store the Media Cache (which is critical to performance when editing and needs to be on big fast storage), so leave at least 100GB free, preferably a lot more. When at my desk, I assign the Media Cache to an external SSD that is only used for caches, providing room for a much larger Media Cache.
I’m looking forward to the next generation of Apple Silicon Mac laptops, because if the higher performance-per-watt (lower CPU temperature) of the Apple M1 is any indication, CPU-intensive applications like After Effects will be able to run faster for longer before heat slows it down, compared to Intel.